ROBERT COSTA: A country and a Congress divided over guns.

I'm Robert Costa.

The gun lobby and Republicans are considering changes in the wake of a tragedy, but they may be narrow, tonight on Washington Week.

A lone gunman armed with a stockpile of weapons turns a music festival into a killing field.

As investigators search for a motive, both parties and the powerful gun lobby may come together to support new restrictions focusing on the device the gunman used to turn his rifles into fully automatic weapons.

HOUSE SPEAKER PAUL RYAN (R-WI): (From video.)

We all know and believe that fully auto weapons are illegal.

And so is this a big gap that needs to be closed, and if so how to close it.

HOUSE MINORTIY LEADER NANCY PELOSI (D-CA): (From video.)

I do think there will be bipartisan support coming together to pass a bill to make it illegal to sell those.

ROBERT COSTA: Will the worst mass shooting in history change the stalled debate?

Plus, President Trump stands by his secretary of state following reports of tensions and name-calling.

PRESIDENT DONALD TRUMP: (From video.)

Total confidence in Rex.

I have total confidence.

ROBERT COSTA: And prepares to abandon the Iran nuclear deal.

We cover it all with Eli Stokols of The Wall Street Journal, Kimberly Atkins of The Boston Herald, Erica Werner of the Associated Press, and Reid Wilson of The Hill.

ANNOUNCER: Celebrating 50 years, this is Washington Week.

Once again, live from Washington, moderator Robert Costa.

ROBERT COSTA: Good evening.

The rampage in Las Vegas that killed 58 people and injured hundreds more has reignited the national debate about firearm regulations.

But the question remains, will that debate translate to political action?

So far, the conversation in Washington has been charged with emotion and it has sparked discussion of law and culture, safety and personal responsibility.

But that next step, just how far the response should go, is still not clear.

What's the difference this time?

Well, the NRA is open to more restrictions on bump stocks, that's the device the Las Vegas sniper used to make his semiautomatic weapons function like an automatic weapon.

But even on that issue, there is debate over whether the Republican-controlled Congress should legislate changes or if any new restrictions should be made by federal regulators.

A number of top Republicans, including Majority Whip Steve Scalise of Louisiana, whose life was nearly taken by a gunman at a baseball field in June, are calling for a review of bump stocks at the Bureau of Alcohol, Tobacco, Firearms and Explosives.

And Scalise says anything else done on Capitol Hill would likely be a slippery slope that threatens Americans' Second Amendment rights to bear arms.

Here are the numbers, some numbers to consider: The Las Vegas shooting was the 273rd mass shooting of 2017, that's according to the nonprofit group Gun Violence Archive, defined as when four or more people were shot and/or killed in a single incident.

Another number: A recent University of Washington study reported that the U.S. has more gun violence than most other prosperous countries.

And a third: Investigators say 12 of the 23 rifles recovered from the Las Vegas gunman were retrofitted with bump stocks.

Erica, that's where the debate stands.

That's where we stand post that horribleness in Las Vegas.

But what about on Capitol Hill?

Are we going to see legislation to get rid of these bump stocks?

Or are we just going to see a tweak to federal regulations?

ERICA WERNER: Well, it remains to be seen and it's probably too early to say, but based on how the debate is starting to turn, it's looking like it's going in the direction of a regulatory change, at least that that would be the preference of Republicans who, of course, would be in the position to bring up legislation.

I mean, as you know, the NRA and congressional Republicans have been totally allergic in recent years to any type of gun controls, so the fact that they even are willing to take a step on anything is significant.

Yet these devices are very little used, confined to kind of a narrow group of enthusiasts, so anything that's done on them is not going to be terribly significant.

ROBERT COSTA: President Trump's the wild card, Eli, in all of this.

ELI STOKOLS: He is, but so far, I mean, he's been much more decisive and emphatic and quick to react in other situations than he was about this.

You suddenly have a White House saying we need to hold back and gather all the facts.

There have been no tweets, you know, from the president saying, well, this is obviously a problem, we need to do this, we need to get tough, as we've seen him do after terror attacks that have been carried out by Islamic terrorists overseas and in the U.S.

So it's obviously not in the president's political wheelhouse to make a big issue of gun control.

I think what's different here and why you're seeing the NRA open the door a little bit to this marginal change on bump stocks, a regulatory change I think is what they prefer, is because Republicans own it in Washington.

You have a Republican president and Republican Congress that will probably be - they need to look like they're responding in a way.

This will give them the semblance of taking some sort of action in response to a horrific event without going further.

When Democrats were in charge, when Barack Obama was president, they wanted to do background checks, they wanted to do a whole lot of things that the NRA would never go for.

This, now that they have a Republican president, there's a political imperative, I think, to allow them to at least appear like they are responding and taking it seriously.

KIMBERLY ATKINS: And there's two different things, right?

There's the appearance that Congress is doing something in the wake of this and there's the policy point, that doing something that will actually make a difference.

I think there is no disagreement, as you pointed out, that this is applying to a very small thing, that most of us probably had never heard of a bump stock before last week.

That's going to do little, you know, the NRA isn't losing much skin in this game by backing this.

But at the same time, it's not really addressing any of the issues that lead to the fact that we have so much gun violence in this country.

I mean, you're talking about some of the numbers, you know, and up to 50 percent of the world's guns is possessed in the United States, civilian-owned guns in the United States, and we have 5 percent of the world's population.

A regulation or a bill banning bump stocks isn't going to do much to change that.

REID WILSON: And this is the NRA's way, though, to control the debate.

And they have an ally in President Trump.

He may not be as beholden to almost any other industry.

When the big Republican groups were abandoning candidate Trump in droves in the late parts of the campaign last year, the NRA was in all of these swing states running advertisements on his behalf.

There is no single interest group in America that has been more solidly behind President Trump.

ROBERT COSTA: But Reid, you cover state legislatures for The Hill and you know that this is about more than just the NRA's position.

There's a culture in many parts of the country.

REID WILSON: Right.

ROBERT COSTA: And there's also many Republican state legislatures, Republican governors who don't want to see any kind of restrictions on guns and that influences debate as much as anything.

REID WILSON: And as a matter of fact, in the wake of the most recent of these horrible attacks, whether it was Sandy Hook or last year in the Pulse nightclub in Orlando, Florida, we've actually seen state legislatures take actions that remove gun restrictions, that allow people to carry openly, to carry concealed weapons without a permit.

That's a constitutional carry that's come up in a number of states this year.

"Stand your ground" laws have advanced in states like Iowa where Republicans now control all levers of government.

So even as the debate sort of stagnates in this normal sort of rhythm that we've gotten into where we talk about guns for a little bit and then it sort of falls by the wayside, action is taking place outside the Beltway and it is not taking place in favor of those who back gun control.

ELI STOKOLS: Don't forget, in 2013 in Colorado after the Aurora theater shooting, the Democratic legislature and governor did enact some gun controls, they passed a tighter background-check law, they passed a law banning high-capacity magazines, and three Democratic lawmakers there were recalled for it.

So if that's a test case, obviously there's a gun culture in Colorado, but it didn't go well politically for those Democratic lawmakers, even though they did respond.

ROBERT COSTA: And Erica, part of the challenge maybe for Democrats on Capitol Hill is that the legislation proposed by Senators Manchin and Toomey, a bipartisan background-check bill that failed a few years ago, now there are many Democrats who say that didn't go far enough, gun-control groups say that didn't go far enough.

So there's pressure from the left to do even more than some kind of bipartisan bill that's been here in the past.

ERICA WERNER: Well, sure.

I mean, you know, if it were up to Senator Feinstein and others, she would renew her assault weapons ban that expired in 2004 after having been in effect for 10 years.

In fact, interestingly, she said this week that she had been planning to do that, considering doing that, but that Senator Schumer asked her to pull back and do a narrower bill just on bump stocks.

Well, now it looks like we're not even going to get that, we're going to get a regulation, Feinstein saying that that wouldn't go far enough, but that, again, will allow Republicans to claim a victory.

ROBERT COSTA: What about, Kim, Steve Bannon, the former White House chief strategist running Breitbart News.

He says that base on the Republican side will erupt if they do any kind of gun control legislation.

KIMBERLY ATKINS: And I think he's right.

I think the NRA and other interest groups that back gun manufacturers and gun accessory manufacturers have done a great job in crafting any sort of gun control measure as a warning sign that the government is trying to take away guns from lawful gun owners, and lawful gun owners don't want that, they're terrified of it.

I don't think that Nancy Pelosi did the left any favors when she said that she wants a slippery slope this week, that she hopes that anything that's done does result in a slippery slope to more legislation.

I think that plays right into the messaging of the NRA.

And I think in the end that that, I mean, it's one of the most powerful lobbies that exists in Washington and statehouses.

REID WILSON: And this gets to a larger point that the gun debate has become as polarized as just about any other debate there is.

Twenty years ago, there were a number of Democrats who were members, not just members of the NRA, but members of the board of the NRA.

Former Congressman John Dingell is one of the reasons that the NRA became such a big political powerhouse.

He encouraged them to do so.

Now there is one party that is almost homogenously in favor of gun control, the Democratic Party, that didn't used to be that way 20 years ago, and one side that is completely homogenously against gun control, that even then there were cracks in the Republican field maybe 25 years ago before the assault weapons ban really cauterized that polarization.

ERICA WERNER: And similarly, the NRA itself used to be much more reasonable, one might say, on these issues, supporting background checks.

One of the things that's happened is that the NRA board has become taken over by industry to a large degree.

And I think that's also why you've seen them be able to move on this issue of bump stocks because bump stocks are not an area of large revenue production at all for the NRA, so it's a relatively easy one for them.

ELI STOKOLS: Well, I think, though, these keep happening and they keep getting worse.

There was a lot made that this was the worst mass shooting in U.S. history, again, this week.

And I think that that will move the debate a little bit and this is the first time we're having this debate in the Trump era with this presidency at a time when so many people in this country, who used to sort of tune out to politics, can't avoid it.

They're plugged into what's going on, they're paying attention to what's happening here in Washington, I think more than they did in past administrations, in part because it just feels so tumultuous and unusual.

And I think that is bringing new voices and new people into these debates.

ROBERT COSTA: Yet where is the legislation?

It seems like it's not prompting a huge legislative push or even an effort from the White House.

It seems to just kind of inch forward the whole process.

ELI STOKOLS: Well, that's right.

And I think with Republicans controlling Congress and Donald Trump in the White House you're not going to see a big legislative push.

KIMBERLY ATKINS: And I think the remarks from Congressman Scalise, of all people, was really remarkable, somebody who was shot by a gunman, saying that it only steeled his resolve to ensure gun rights and that people need these guns to protect themselves.

Of course, that wouldn't have happened in this case of Las Vegas.

Even if everyone in that crowd was armed, that wouldn't have stopped this gunman.

But it just shows how remarkably strong the Republican position is on this.

ROBERT COSTA: And we'll have to watch, Erica, what exactly comes down the pike here, because Representative Carlos Curbelo of Florida, a moderate Republican, he's working on legislation to ban bump stocks.

Even if there is a regulatory change, he wants to see it legislated.

You have Congressman Pete King of New York and Democrats working on a background-check bill in the House, so there are glimmers of action.

ERICA WERNER: There are, yeah, but at the same time, when you listen to the comments from key committee chairmen, Grassley of Judiciary in the Senate and Goodlatte in the House, it's kind of along the lines of, yes, we'll look at this, but let's wait until the investigation finishes and then we'll hold hearings.

I mean, that's where things go to kind of peter out.

So I don't see anything dramatic happening anytime soon.

ROBERT COSTA: And, Reid, the Scalise moment was a telling one this week on Capitol Hill, someone who was shot, someone in the Republican leadership saying that the whole experience of being shot, his word, fortified his support for gun rights.

REID WILSON: And this is where the Republican Party is these days.

You know, there are calls in the wake of a shooting like this to not talk about the politics right now.

And that's sort of a code word for let's wait until this all dies down and then we can let the debate die down.

That's what's happened again and again.

Scalise welcomed back, was it last week or this week?

These weeks are blending together.

Welcomed back as a hero, given a standing ovation, a bipartisan welcome back on the floor of the House.

Then again, he is still the number-three Republican in the House of Representatives and he's not going to change the caucus's view.

ROBERT COSTA: Well, we'll keep a close eye on everything as it moves forward, whether it's a bill or whether it's some kind of ATF change to the federal law and federal regulations.

Meanwhile, beyond the gun debate, the Trump administration is also confronting a number of urgent foreign policy matters, including Iran and North Korea.

President Trump is planning to abandon the Iran nuclear deal, despite the fact that some of his top advisers, including Secretary of State Rex Tillerson and Defense Secretary James Mattis, support the agreement.

Mattis testified before the Senate Armed Services Committee on Tuesday, and when Senator Angus King asked him about the Iran deal, here's what he had to say.

SENATOR ANGUS KING (I-ME): (From video.)

Do you believe it's in our national-security interest at the present time to remain in the JCPOA?

SECRETARY OF DEFENSE JAMES MATTIS: (From video.)

Yes, Senator, I do.

ROBERT COSTA: Two days later, Mattis was sitting next to the president during a White House briefing.

Here's what Mr. Trump had to say.

PRESIDENT DONALD TRUMP: (From video.)

The Iranian regime supports terrorism and exports violence, bloodshed and chaos across the Middle East.

That is why we must put an end to Iran's continued aggression and nuclear ambitions.

They have not lived up to the spirit of their agreement.

ROBERT COSTA: This is a deal for President Trump, a deal he's trying to change.

ELI STOKOLS: Well, he wrote The Art of the Deal.

This is part of his DNA and his own self-conception that he thinks that all the deals that his predecessor, Barack Obama, made are terrible, they're weak, the U.S. gave too much away, and he thinks he can make a better one.

He threw out the Paris agreement for the same reason.

He's taking a lot of Obama's domestic accomplishments, the Clean Power Plan is another one that they're moving to repeal this week, so this is not an isolated instance, this is just one that has huge geopolitical ramifications.

And the president is making foreign policy much the same way he makes domestic policy, based on this sort of antipathy and loathing for multilateralism and also a continued need to erase any trace of accomplishment from the Obama administration.

And yes, there are adults in the room, the people who are supposedly the adults, the people Bob Corker says are separating the country from chaos.

ROBERT COSTA: Senate Foreign Relations Committee chairman.

ELI STOKOLS: That's right.

But this is a president who, as you know, when people sort of try to box him in and say you can't do this, what does he do?

He's more resolved to do it.

REID WILSON: That's a very good point.

This is the consummate - what we've learned about this president is that if the establishment, if other nations tell him that this is the way that things work in the system, he's going to try to blow up that system.

And this is a key example of it.

Trump's actions will not entirely end the U.S. involvement in the deal.

It will kick some action to Congress, they'll have 60 days to decide whether or not to roll back or snap back the sanctions into place.

And that gives him a little bit of wiggle room, but a little bit of wiggle room on the international diplomatic stage is not great for somebody who in his first nine months in office has not completed a major deal.

ROBERT COSTA: Well, let's say it goes to Capitol Hill, Erica.

The Republican leadership, they're mostly hawks, how do they handle that?

ERICA WERNER: Well, for one thing, they really would prefer not to.

And this is not the first time where Trump is throwing Congress something that they don't really want on their plate while they have a lot of other stuff on their plate.

And his tendency is then to blame them for whatever transpires.

But it's kind of a tough spot for Republicans in that they were ferociously, unanimously opposed to this deal when Barack Obama was passing it two years ago, I mean, uncompromisingly.

That said, there does not seem to be an appetite to snap back those sanctions.

What Tom Cotton wants to do, and others will take their cues from him because he's been out front on this, is to try to find some way to renegotiate the terms of the deal, as kind of far-fetched as that might seem.

ROBERT COSTA: It sounds like Eli when he mentioned the Paris accords.

It's trying to - ELI STOKOLS: Well, the president had lunch with Tom Cotton at the White House yesterday and, I'm told from someone familiar with the conversation, asked Cotton for the speech that he gave at the Council on Foreign Relations this week.

So when we hear the president come out with his case, he's likely to sort of lay out the same thing, the same argument that Cotton said, let's take the 60 days, let's see if it gives us leverage to negotiate something better.

I just don't know if the Iranians are really in the mood to negotiate - ERICA WERNER: Right.

KIMBERLY ATKINS: Right.

ELI STOKOLS: - much less the other powers that were party to the deal.

KIMBERLY ATKINS: And that was originally the point of the original deal.

It wasn't to end, nobody thought it would end Iran's nuclear program.

It gave some time, it bought some time, essentially, to try to see if you can use some diplomatic measures to go forward.

So that's what the deal itself was meant to do.

But the president, as you said, is so determined to get rid of it, but, again, giving himself some buffer room, really kicking it to Congress to make that decision.

It reminds me, after Obama and the red line was drawn, he subsequently kicked that decision to Congress and ultimately nothing happened.

ROBERT COSTA: And there are costs, Erica, to if the U.S. gets out of the deal.

Last month, Iranian President Hassan Rouhani said there would be a high cost.

You have North Korea watching very closely.

Will the U.S. keep its word on a nuclear agreement?

KIMBERLY ATKINS: Right.

ERICA WERNER: And you have our allies that are part of this deal.

You know, what are we saying to the world as we pull out of these international agreements?

What if something happens on North Korea, we need help from these same players?

So it sets a precedent and it's one that could have serious consequences for our country.

ROBERT COSTA: Reid, we're also watching Secretary of State Tillerson twist in the wind.

What a week for him as he's really - people, the whole town, the whole city is talking about possible resignation or at least a secretary of state that's on the ropes.

How much time does he have left?

And has this relationship totally eroded?

REID WILSON: We're all sitting here checking our Twitter feeds before we go on air to make sure that he hasn't resigned yet.

That seems to be the president's way, on Friday nights he likes to fire people.

Secretary Tillerson, a report this week, apparently called President Trump a name in a meeting.

That did not go terribly well.

And this relationship, from everything that I have heard, it's been on the rocks for a very long time.

Secretary Tillerson has had a difficult time transitioning into this role.

The White House has been angry with the State Department and their slow pace of actually filling the jobs that are sort of necessary to set a president's foreign policy.

And then he has struggled as well to demonstrate that he really represents the word of the president of the United States of America, and that is the single-most-important thing for a secretary of state of state to do.

Now as this relationship degrades, his standing on the world stage becomes even weaker.

And it's become sort of a self-fulfilling spiral towards the bottom that, you know, his end could come any moment.

ROBERT COSTA: Take us inside the White House, Eli.

Is he on his way out?

ELI STOKOLS: We talked to people today who said, no, we think he has some time, but nobody ever really knows.

I mean, this is a president who consumes so much television and for 48 hours now since the Tillerson press conference, what has he probably been hearing back to him?

Television personalities saying Rex Tillerson did not deny calling President Trump a moron.

Well, that's making Trump seethe.

And so, yes, he already has two vacant Cabinet positions, yes, that's a problem, they would like to sort of stretch this out and maybe not have this blow up in their face right now.

But can Trump live with it?

That's the question and that's really, at the end of the day, the only thing that matters, is can President Trump live with this?

ROBERT COSTA: And, Kim, they're floating replacements already.

CIA Director Mike Pompeo, U.N.

Ambassador Nikki Haley, these names are everywhere.

KIMBERLY ATKINS: Yes.

And that has got to make Secretary Tillerson's job even more difficult.

I mean, it's no fun working at the State Department right now from the top on down.

But then think about that, yes, we already have two vacancies.

If you use either Pompeo or Haley in this position, then who becomes the next CIA director or who becomes the next U.N. ambassador?

ROBERT COSTA: You have a big confirmation fight, too.

KIMBERLY ATKINS: You have confirmation fights.

Meanwhile, North Korea is still a threat.

Meanwhile, we still have to deal with what the decision's going to be on this nuclear reauthorization of the Iran deal.

It's a tough time right now and it's tough to recruit people to this administration.

ROBERT COSTA: And, Erica, just to close us out, this whole experience watching the secretary of state this week, it's indicative of how if you don't have a rapport, a personal rapport with this president, you're probably in trouble.

ERICA WERNER: Yeah, that's absolutely right.

And with Tillerson as well, you'll recall back to when he initially got confirmed, he had trouble winning the Hill over.

And there's not going to be a lot of love lost from the Hill either if he goes.

He just never made close contacts on the Hill, nor in the White House.

He was kind of isolated, it seemed, within the State Department as well, so it can't be too much longer for him to be sticking around.

ROBERT COSTA: Is there anyone on your radar as you're talking to congressmen and senators on Capitol Hill?

ERICA WERNER: Well, Nikki Haley is someone who has a lot of respect; Pompeo, of course, from the House; so either of those.

ROBERT COSTA: And do they both have that rapport with the president?

ERICA WERNER: Well, I think they appear to more than Tillerson.

I mean, it could hardly get worse than him, so we'll see.

ROBERT COSTA: We'll have to leave it there tonight.

And we'll all be on Tillerson watch this weekend and I guess for the next few days and weeks.

Thanks everybody for being here.

Appreciate it.

And our conversation as ever will continue online on the Washington Week Extra, where we'll talk about the Trump administration's decision, a big one, to roll back the mandate that it requires employers and insurance companies to cover birth control.

You can find that later tonight at PBS.org/WashingtonWeek.

I'm Robert Costa.

Have a great weekend.