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U.S. Senate Majority Leader Mitch McConnell (R-KY) and Sen. John Barrasso (R-WY) leave a Republican policy lunch on Capito...

Trump’s emergency declaration faces a Senate vote. Here’s what to expect

Next week, the U.S. Senate will be at the center of a rare, intraparty face-off between branches of government, as the Republican-led chamber votes on whether to end President Donald Trump’s national emergency designation for the southern border. For the GOP in particular, the issue presents a dilemma, pitting concerns over balance of power and military construction funds against loyalty to Trump, who is seeking more funding to build a border wall.

Here is a look at the political calculations right now, and how it could play out.

What is the vote exactly? Senators will vote on a measure disapproving of and terminating the president’s emergency declaration. The initial wording is the same resolution passed by the House last month. However, it is not clear if the Senate can or will try to amend that text before voting.

Will it pass the Senate? Yes, most likely.

Explain more, please. Sure! This legislation falls under special rules and needs a simple majority in the Senate to pass. So far, all 47 Democrats/Independents are on board, as are four Republicans. That gives it the 51 votes needed to pass.

Who are the four Republicans voting against the Trump emergency currently? Sens. Susan Collins of Maine, Lisa Murkowski of Alaska, Rand Paul of Kentucky and Thom Tillis of North Carolina have all announced they will vote to end the emergency declaration.

How many undecided Senate Republicans are there? By NewsHour’s count, roughly 20 additional Republican senators are in play at the moment and could vote either way.

Who is on that undecided list? There is no clear-cut list, as private conversations are ongoing. But we recommend watching the following GOP senators: Barrasso, Blunt, Cassidy, Gardner, Inhofe, Isakson, Johnson, Lankford, Lee, McSally, Portman, Roberts, Romney, Rubio, Sasse, Sullivan, Toomey, Thune, Wicker and Young.

If it passes the Senate, would Trump veto the resolution? Yes, he has said he would.

How many votes would be needed to override the president’s veto? This is the key question. Overriding a veto requires two-thirds of the senators present. If all 100 attend the vote, that means 67 votes.

Is a veto override possible? In the Senate currently, yes. But it would be difficult, requiring 16 Republicans who are currently undecided to break with the president.

Wait, is a veto override possible in the House? Better question. The current thinking on the Hill is that this is nearly impossible. Just 13 House Republicans voted to end the emergency declaration last month. To override the president, another 44 Republicans would need to vote with Democrats.

What’s going to happen? It seems certain Congress will vote to end the emergency declaration and then the president will veto that decision, keeping the emergency in place. Unless Congress is then able to override the president, the final decision is most likely to come from the third branch of government — the courts — where lawsuits are already in motion.