Sarah Silbiger/The New York Times
WASHINGTON — Senator Mitch McConnell, the majority leader, conceded on Monday that he could not stave off final passage of a resolution overturning President Trump’s national emergency declaration, setting up a rebuke to Mr. Trump amid signs that the president’s grip even on his own party in Congress may be slipping.
With Senator Rand Paul of Kentucky joining three other Republicans — Susan Collins of Maine, Lisa Murkowski of Alaska and Thom Tillis of North Carolina — in announcing he would support the measure, Democrats now have the 51 votes they need to secure passage and to force Mr. Trump to issue the first veto of his presidency.
Mr. McConnell is exploring whether he can amend the House-passed resolution of disapproval, to send it back to the House and slow its trip to the president’s desk. Ms. Collins and Ms. Murkowski are both sponsors of a separate resolution, virtually identical to the House resolution, introduced in the Senate last week.
And while a veto is highly unlikely to be overturned, the congressional majority that forces it will stand as a powerful rejection of the tactics Mr. Trump has used to fulfill his top campaign promise to build a wall on the southern border — and will apparently be the first time since passage of the National Emergencies Act of 1976 that Congress has voted to overturn an emergency declaration.
“It simply sends a message that Congress is going to stand up for its institutional prerogatives and abide by the separation-of-powers framework that was carefully worked out by the framers in the Constitution,” Ms. Collins said on Monday. “I truly don’t see this as sending a message at all one way or the other about border security but rather about executive overreach.”
Ross K. Baker, a political scientist and expert on Congress at Rutgers University, said passage of the resolution would amount to a “serious rebuke” of the president.
“It’s Congress saying: ‘This has gone far enough. We’re not going to roll over and play dead for the president,’” Mr. Baker said. “It’s the kind of thing that James Madison had in mind when he laid out in the Federalist Papers the argument for separation of powers and checks and balances.”
Mr. McConnell has not set a date for the vote, but it is expected before March 15, when lawmakers leave for recess; Mr. Paul said on Monday that he believed as many as 10 Republicans would vote for the resolution. Once Mr. Trump issues his expected veto, the matter is all but certain to be settled in the courts, where multiple lawsuits have been filed.
Speaking at an event in his home state of Kentucky on Monday, Mr. McConnell offered a matter-of-fact assessment of the reality facing the White House: “I think what is clear in the Senate is there will be enough votes to pass the resolution of disapproval, which will then be vetoed by the president and then in all likelihood…
