GWEN IFILL: A Supreme Court nominee and a shrunken presidential field, what both of these events tell you about the state of our politics, tonight on Washington Week.

PRESIDENT BARACK OBAMA: (From video.)

I have fulfilled my constitutional duty.

Now it's time for the Senate to do theirs.

GWEN IFILL: The gauntlet thrown down in the Rose Garden as the president nominates Judge Merrick Garland to the nation's highest court.

JUDGE MERRICK GARLAND: (From video.)

This is the greatest honor of my life.

GWEN IFILL: And Washington braces for an unprecedented fight.

SENATE MAJORITY LEADER MITCH MCCONNELL (R-KY): (From video.)

Republicans think the people deserve a voice in this critical decision.

The president does not.

SENATOR CHARLES SCHUMER (D-NY): (From video.)

The message from the American people to Senate Republicans is simple: Do your job.

GWEN IFILL: Will the president's nominee ever get a hearing, let alone a vote?

On the campaign trail, Hillary Clinton and Donald Trump sweep.

FORMER SECRETARY OF STATE HILLARY CLINTON: (From video.)

We are moving closer to securing the Democratic Party nomination and winning this election in November.

DONALD TRUMP: (From video.)

We're going to go forward and we're going to win.

But more importantly, we're going to win for the country.

GWEN IFILL: Marco Rubio is swept out of the race after losing his home state, as Ted Cruz and John Kasich plot their way to a contested convention.

SENATOR TED CRUZ (R-TX): (From video.)

Tonight we continue to gain delegates and continue our march to 1,237.

OHIO GOVERNOR JOHN KASICH (R): (From video.)

We are going to go all the way to Cleveland and secure the Republican nomination.

(Cheers, applause.)

GWEN IFILL: On the Democratic side, Bernie Sanders declares he's not quitting.

SENATOR BERNIE SANDERS (I-VT): (From video.)

We think we've got a path toward victory.

(Cheers.)

And if we can bring out large turnouts, we're going to win this thing.

GWEN IFILL: Covering the week, Pete Williams, justice correspondent for NBC News; Peter Baker, chief White House correspondent for The New York Times; and Karen Tumulty, national political correspondent for The Washington Post.

ANNOUNCER: Award-winning reporting and analysis.

Covering history as it happens.

Live from our nation's capital, this is Washington Week with Gwen Ifill.

Once again, live from Washington, moderator Gwen Ifill.

GWEN IFILL: Good evening.

Well, we've been waiting for a lot of shoes to drop, and several hit the floor this week.

We start with the tale of Merrick Garland, a jurist with such an impressive resume that even Republicans say they have no problem with him, personally.

But this nomination is personal in a different way, which the president himself acknowledged even as he was introducing Garland in the Rose Garden and in an NPR interview yesterday.

PRESIDENT OBAMA: (From video.)

You cannot point to me a circumstance in which Democrats have left a seat open when a Republican president was in office simply because they didn't like the possibility that it would change the makeup of the Court.

GWEN IFILL: But Republicans say precedent is not the point.

I talked to Senator Orrin Hatch this week on the NewsHour.

SENATOR ORRIN HATCH (R-UT): (From video.)

We ought to put this off until the next election - or until after the election so that it's fair to both sides and we get it out of this really - what really is a toxic presidential election process.

GWEN IFILL: He said that toxic thing about five times.

The options?

Meet the guy, but not hold hearings.

Hold hearings, but not confirm him.

Wait it out for a lame duck session after the election.

Or, don't do anything at all.

First, tell us about Merrick Garland, Pete.

PETE WILLIAMS: Well, it's hard to imagine a Democratic nominee that would be more acceptable to Republicans than Merrick Garland.

He's well-liked, well-respected.

And probably that's one of the reasons the president nominated him, because he knew it would be harder for a lot of Republicans to oppose him.

Born in Chicago, grandson of Russian immigrants, Harvard, Harvard Law.

Was a prosecutor in the Oklahoma City case and went to Oklahoma City.

And I think that's a very important part of what makes Merrick Garland the person that he is, because if you look at his rulings he tends to be deferential to federal agencies, but tough on criminal defendants.

So he has that sort of duality.

He's been on the Court of Appeals.

He's now the chief judge of the Washington, D.C. Court of Appeals for 19 years.

Let me tell you what a careful man he is.

During his speech in the Rose Garden he said, I've served for 18 years.

He was three days shy of 19, but he said 18.

That's the kind of careful person he is.

He was confirmed in 1997 by the Senate 76 to 23.

He had 32 Republicans voting for him, seven of whom were still in office.

So he's - GWEN IFILL: And he's been on the shortlist for a long time.

In 2010 you were on this program at this table, and you said he was on the shortlist even then.

PETE WILLIAMS: Well, he was when the president considered Sonia Sotomayor and again when the president considered Elena Kagan.

He was left at the altar both times.

And I think the president liked him in the previous two sessions.

That's the impression that we've gotten.

And I just think that this was the time.

He said he's the right man for the job, meaning that politically he's the best fit.

He never really questioned whether he'd be a good judge or not.

GWEN IFILL: Well, Pete, let's talk about precedent - Peter.

(Laughter.)

There's too many - PETE WILLIAMS: Not nearly enough.

(Laughter.)

GWEN IFILL: Never enough.

Tell us about the precedent here.

What it is that the Republicans are doing, sticking their heels in here, has never happened before.

PETER BAKER: No, not like this.

I mean, there have certainly been instances where a Senate of one party has rejected or stalled on nominees of the other president's party in an election year, but nothing like this where they've basically tried to hold out for an entire year - not in modern times, anyway.

There was some 19th century stuff we could go into.

GWEN IFILL: Or not.

PETER BAKER: Or not.

(Laughter.)

But this is, in fact, unprecedented in that sense.

And this is what Merrick Garland was intended for.

The president did consider him in '09 and '10 again.

And he was the in case of emergency break glass candidate, right?

The president didn't need an emergency candidate at that point, because he had a Democratic Senate.

So he went with a candidate, first Sotomayor and then Kagan, who would be more daring and presumably more appealing to the liberal base.

Garland was always sort of the safe choice because they did have Republican support in the past.

This is the moment they've been waiting for.

When do you put up Merrick Garland?

When you have a Republican Senate that doesn't want to pass your person.

Now, will he be confirmed before the election?

Doesn't look like it right now.

The president's pushing for it.

But what people are really talking about is could he be confirmed in the lame duck session after the election?

PETE WILLIAMS: By the way, you played that sound from Orrin Hatch at the beginning.

He has retreated from what he said since then.

He did come out and say, you know, the option of a vote after the presidential election was one that he thought maybe he could go for.

Since then, he's had a little talk with the leadership and he no longer says that.

GWEN IFILL: And did the leadership point out that the Congress would be lame duck as well?

Did that maybe change his mind?

PETE WILLIAMS: Well, no.

But they're all on board right now, although Mark Kirk, who's facing a tough reelection campaign and is from Illinois, Merrick Garland's home state, did say today that he deserves - Garland deserves a vote.

GWEN IFILL: Actually, what he said is they should man up and vote.

PETE WILLIAMS: That's right.

GWEN IFILL: Karen.

KAREN TUMULTY: Well, part of that, though, especially - there's some fear on the part of Republicans that especially if Donald Trump is at the top of their ticket that they could actually lose the Senate, that Hillary Clinton could be elected.

If that were the case, if we were looking at in December a President-Elect Clinton, what would be the chances that she too would go with Judge Garland?

PETER BAKER: Yeah, it's a great question, right?

In fact, in some ways, the most important question.

Does his nomination survive beyond this administration?

And I think that's why you hear Republicans making the noises about possibly making a lame duck vote because in fact if Hillary Clinton were to win, he would be the best option they would get.

PETE WILLIAMS: In fact, Senator Jeff Flake said as much.

And let me just read his quote to you.

He said - I thought I had it here; yes, I do - he said: I would rather have a less-liberal nominee, like Merrick Garland, than the nominee that Hillary Clinton, if she were president, would put forward.

So that's what they're all thinking.

GWEN IFILL: They have to be thinking that way.

OK, well, let's go back a little bit.

I want to give you a little history.

This is Joe Biden.

He was then a senator from Delaware.

He was speaking on the Senate floor in 1992.

SENATOR JOSEPH BIDEN (D-DE): (From video.)

It would be our pragmatic conclusion that once the political season is underway, and it is, action on a Supreme Court nomination must be put off until after the election campaign is over.

That is what is fair to the nominee and essential to the process.

GWEN IFILL: Important point, there was no opening on the Court at the time.

And this was Orrin Hatch speaking in favor of Merrick Garland on the Senate floor in 1997.

SENATOR ORRIN HATCH (R-UT): (From video.)

And I believe Mr. Garland is a fine nominee.

I know him personally.

I know of his integrity.

I know of his legal ability.

I know of his honesty.

I know of his acumen.

And he belongs on the court.

GWEN IFILL: Another important point, Garland was then up for a Court of Appeals judgeship, the one he holds now.

What is different?

PETE WILLIAMS: Well, one of the things - the Republicans have talked a lot about that Biden speech there.

And Mitch McConnell - GWEN IFILL: They call it the Biden rule.

PETE WILLIAMS: Mitch McConnell even this week called it the Biden rule.

But if you look at the entirely of what - you know, this was Biden speaking after the Bork debacle.

And he was trying to say, how can we get the nomination process back on track?

What he said is: In a presidential election year, A, I would urge a president not to nominate somebody in the heat of a campaign.

But if the president does, what he said is, the Judiciary Committee should not schedule hearings until after the campaign season is over.

He didn't say no vote, no how.

He said, let's wait until November.

PETER BAKER: Right, but that may be in fact what ends up happening here, that they wait until after the election season is over.

In that case, he was talking in June of an election year, as you say, with no nominee to be made.

This is March.

There's a longer period of time.

And Biden says, look, you're misinterpreting what I am saying, but - GWEN IFILL: Which has never happened before, never in Washington.

PETER BAKER: Never happened before.

PETE WILLIAMS: And by the way - PETER BAKER: It was a Republican president then and a Democratic Senate.

Now we have a Democratic president and a Republican Senate.

GWEN IFILL: Depends where you sit.

PETE WILLIAMS: That same day, the ranking Republican on Judiciary, Strom Thurmond, came to the Senate floor and said: There's no election year exception.

(Laughter.)

So things do change.

GWEN IFILL: They change.

KAREN TUMULTY: What about the ideological makeup of the court if a - if Justice - you know, if Justice Scalia were to be replaced by a, you know, Justice Garland?

PETE WILLIAMS: Well, that's really what this is all about.

And that's why the Republicans feel so strongly here, that you're replacing the sort of conservative fireplug of the - spark plug of the Supreme Court with somebody who will just not - with any Democratic nominee's appointee is going to move the court to the left.

It's ideologically split four to four now.

You're going to make it five to four the other way than it was with Scalia.

And that's why the Republicans don't want a Democrat to replace Antonin Scalia.

GWEN IFILL: Well, now we see a slight shift in strategy in that at least 11 Republicans are saying they're willing to at least meet the guy.

He seems like a nice enough fellow.

He loves his wife and children.

But that doesn't necessarily mean that it's moving them away from the goal, or does it?

PETER BAKER: Well, there's a real debate inside the conservative - well, I mean, it does in a way.

But the debate in the Republican side, how much do you make the fight about the process - that is, we shouldn't have anybody until after the election, just let the voters decide, and how much do you make it about Merrick Garland and his own particular merits or drawbacks?

And they're a little torn about that, because in fact if they do end up deciding that they want to confirm him after the election because they don't want a Hillary Clinton appointment that might be worse, they don't want to beat him up so much that they can't walk it back and say, you know, let's go ahead and put him on the Court.

And he has a record that's more complicated than a straightforward liberal nominee.

GWEN IFILL: Well, I haven't heard anybody raise any questions yet about that record.

And I don't know that there is anything about his social - his social policy stands or that he's written.

PETER BAKER: The biggest one is gun rights, where he was involved with the Heller case that ultimately was written by Scalia that found a Second Amendment right for individuals to own a gun.

And you do hear conservative groups - PETE WILLIAMS: He didn't say he was opposed to that, by the way.

PETER BAKER: No.

PETE WILLIAMS: What happened is a three-judge panel here in Washington said: There is an individual right to own a gun, which is what the Supreme Court ultimately agreed with.

He said, you know, we ought to reargue that before the whole panel.

Now, you would think if he endorsed it 100 percent he wouldn't have said that, but maybe there was a procedural ruling and maybe - or a procedural reason.

And also, it was, in a sense, bucking what everybody thought was the court's rule.

GWEN IFILL: Well, perhaps it's complicated issues like that the reason why they hold hearings.

(Laughter.)

But I - PETE WILLIAMS: What a concept.

GWEN IFILL: It is a concept.

Now we're going to move on to the 2016 campaign.

For two candidates, the path to presidential nomination became much more clear this week.

With five more states under her belt, Hillary Clinton has now accumulated 1,614 delegates, which include 467 superdelegates, which gives her more than half of what she will need.

And Donald Trump has accumulated 678 delegates, 559 short of the total he needs.

For some reason, these numbers have not scared three other remaining candidates out of the race.

John Kasich, who has won only his home state of Ohio, is pushing for a contested convention.

OHIO GOVERNOR JOHN KASICH (R): (From video.)

Politics is so crazy, you never know what'll happen.

But they're going to look at somebody who could actually be president of the United States, who has a record of accomplishments, not just talk.

And secondly, they're going to wonder about who can win a general election, who can win Ohio.

GWEN IFILL: Ted Cruz longs for a one-on-one face-off with Trump.

SENATOR TED CRUZ (R-TX): (From video.)

Now is the time for Republicans to unite, for independents to unite, for libertarians to unite, for all of us who want a brighter future for our nation to come together and stand as one.

GWEN IFILL: And Bernie Sanders hopes his grassroots appeal will make him impossible to ignore.

SENATOR BERNIE SANDERS (I-VT): (From video.)

I'm proud that up to now we have won nine states.

We have almost 850 delegates.

(Cheers.)

And with your help on Tuesday, we're going to win here in Arizona.

(Cheers.)

GWEN IFILL: OK, that's Bernie's delegate math.

Now, we have Karen here to do a little delegate math for us.

Which of these guys has a shot?

KAREN TUMULTY: It is now mathematically impossible for John Kasich to get to the convention with the number of delegates he needs.

He would need to win something like 110 percent of the remaining delegates.

GWEN IFILL: Or, as our friend John Dickerson said, actually add states to the Union.

(Laughter.)

KAREN TUMULTY: Right.

And then there is a narrow path for Ted Cruz.

He would have to win something like 80 percent of the remaining delegates.

But there is, you know, a path for him, which is why you saw something very significant happen today, which is that the last - the 2012 Republican nominee, Mitt Romney, who on - you know, earlier this week was in Ohio campaigning with John Kasich, announced that in the Utah caucuses next Tuesday he will be casting his vote for Ted Cruz, and that he thinks everyone who wants to stop Trump from here on out needs to be voting for Cruz in every single one of these contests.

GWEN IFILL: OK, you have to explain this to me, because I thought it was last week, but you're right, it was just this week he was campaigning with John Kasich.

Tell me, what is the reasoning here that you just vote for the strongest guy in every state, who's not named Trump?

KAREN TUMULTY: It was - yeah, you vote for the only guy - the only person who is left standing between Donald Trump and the nomination, which is also why you had former presidential candidate and Senator Lindsey Graham giving his kind of weird semi-endorsement of Ted Cruz, who only three weeks ago he was at one of these press dinners in Washington making jokes about, you know, the possible murder of Ted Cruz.

And by this week, he was saying, well, I'll be at that fundraiser for him next week.

So it's really ironic, and it just tells you how crazy this year is, that of all people Ted Cruz has become the last hope of the Republican establishment.

PETER BAKER: So if neither Cruz nor Kasich is likely, let's say, to get the majority before the convention, what is the scenario going forward then?

In other words, what do they hope to actually see happen at this convention and how plausible is that?

KAREN TUMULTY: Well, it's interesting because as many years as I've been covering politics, I never actually had to do any research until this week into exactly how you become a delegate.

But it's a really complicated process.

And it's generally going to happen - even though we've had all these primaries and caucuses, very few of the actual delegates have been picked.

So there are going to be all these fights in the states over the next couple of months.

PETE WILLIAMS: But the number has been picked, right?

The number of delegates - KAREN TUMULTY: The numbers have been picked, but the people who fill the chairs on the convention floor have not.

So when those people get to the convention, they will be - almost all of them will be bound on the first ballot to vote however their state voted.

But if it goes beyond that, if for some reason Donald Trump, presumably, doesn't have those numbers and it goes to another ballot, they are essentially free agents.

And depending on the machinations in all these states for how they're picked, they could actually turn out to be sleeper cells for other candidates.

(Laughter.)

PETER BAKER: But in the era long before - sorry - in the era long before primaries, conventions often picked people who were not the frontrunner on the first ballot.

But can we imagine that happening today?

What would be the reaction?

What would - I mean, Trump has already told us what he thinks the reaction would be.

GWEN IFILL: Riots, I think is the term he used.

KAREN TUMULTY: Yeah, Donald had predicted there would be riots.

But it would be - it would be a real dilemma for people who think that Donald Trump at the top of the ticket would be a disaster for the Republican Party, not just in the presidential race but potentially costing all the way down the ballot.

So they are going to have to sort of decide whether that is a worse alternative, or turning their backs on a plurality of their own voters would be - PETE WILLIAMS: But if Ted Cruz has to get 80 percent of the delegates from here on in order to forestall that, it doesn't seem like it's going to happen.

On the first ballot would elect Trump.

KAREN TUMULTY: It is - it is - well, it is very - but it could be that he gets enough that Trump doesn't get half - PETER BAKER: He needs 80 percent to get the majority.

He doesn't have to have the majority to stop Trump from getting the majority.

PETE WILLIAMS: Ah, OK. KAREN TUMULTY: Yep.

GWEN IFILL: So does that mean that under the surface while we're watching states and we're watching primaries, there's a secondary fight going on for individual delegates, picking people who might not be for you now but might be for you later?

KAREN TUMULTY: And in places - for instance, South Carolina, Donald Trump won all 50 delegates of South Carolina.

But those delegates are going to be picked at a state convention among party regulars, whose loyalties are really, you know, to people like Governor Nikki Haley and Senator Lindsey Graham who have had their - you know, had their tussles with Donald Trump.

So this is going to be - this drama is going to be playing out on two, and three, and four levels.

GWEN IFILL: So is this the only - is this the most viable, or the only viable stop Trump strategy?

Or is there really a viable stop Trump strategy at this point?

KAREN TUMULTY: The convention is the - is really and truly the only one.

But every other Trump strategy - stop Trump strategy has only succeeded in making Donald Trump stronger.

GWEN IFILL: Let me ask you briefly about Bernie Sanders.

What is his path, other than big turnout?

KAREN TUMULTY: Bernie Sanders - the Democrats do things differently.

Where a lot of the Republican primaries from here on out are going to be winner-take-all, the Democrats do all their primaries proportionally, which means that Bernie Sanders is going to keep picking up delegates.

He's got an enormous fundraising operation, and he's got a message.

So there's really not a lot of incentive for him to get out of this race, which he, by the way, says he can still win.

He says he can win California.

He says that the map is going to start playing his way.

GWEN IFILL: You and I first met covering the Jessie Jackson campaign in 1988.

We were very, very small children.

In that year - KAREN TUMULTY: I was covering it for my elementary school paper, yes.

PETER BAKER: School paper?

KAREN TUMULTY: Yes.

GWEN IFILL: Exactly, elementary school.

But he was collecting delegates even he stopped winning, so that when he got to the convention he had a really big place to be.

He had a platform.

KAREN TUMULTY: And he did - I mean, the fundraising capacities that Bernie Sanders has will also just keep him going.

And you know, again, there's really not a lot of incentive for him, for quite a while, to get out of this race.

GWEN IFILL: OK. Well, and it keeps on rolling.

Thank you very much, all of you.

We have to go a few minutes early again this week to give you the chance to support your local station, which in turn supports us.

But the conversation continues online on the Washington Week Webcast Extra where, among other things, we'll preview the president's historic trip to Cuba.

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Good night.