President Trump speaks during a briefing on drug trafficking at the southern border in the Roosevelt Room of the White House on Wednesday. (Evan Vucci/AP)

The Senate prepared Wednesday to rebuke President Trump over his national emergency declaration at the U.S.-Mexico border, after Trump rejected a GOP compromise aimed at curtailing presidential emergency powers in the future.

Sen. Mike Lee (R-Utah), who was leading the compromise efforts, announced plans to defect and vote for a resolution to nullify Trump’s emergency declaration when it comes to the floor on Thursday. Lee made the announcement shortly after hearing directly from Trump that his legislation was not acceptable.

“For decades, Congress has been giving far too much legislative power to the executive branch. While there was attention on the issue I had hoped the ARTICLE ONE Act could begin to take that power back,” Lee said in a statement, referring to his legislation giving Congress a greater say in national emergency declarations.

“Unfortunately, it appears the bill does not have an immediate path forward, so I will be voting to terminate the latest emergency declaration,” Lee said.

Lee’s position all but ensures there will be majority support in the Senate on Thursday for the disapproval resolution, which already passed the House. Senate passage would send the measure to Trump, forcing him to issue the first veto of his administration to strike it down.

Although Congress lacks the votes to override Trump’s veto, the Senate vote would still stand as an embarrassing rebuff of a key Trump initiative at the hands of his own party. And it will come a day after a Senate vote to end U.S. support for the Saudi-led war in Yemen, marking unusual twin rebukes from a Senate that has mostly bowed to Trump’s wishes.

Trump declared the national emergency Feb. 15 as a way to circumvent Congress and get the money he wants to build barriers along the southern border. The president has framed the issue in terms of national security, whereas Lee and some other Republicans have focused on the constitutional issues at stake in Trump intruding on Congress’s control over government spending.

Lee’s fellow Republican senators embraced his effort to craft legislation curtailing the scope of presidential emergency powers going forward, saying it could limit GOP defections on the separate disapproval resolution vote.

Four GOP senators had announced plans to vote against Trump and for the disapproval resolution Thursday, giving it the majority support needed to pass. But one of those senators — Thom Tillis (R-N.C.) — had indicated his vote could be in play depending on the outcome of the negotiations over Lee’s legislation. That raised the possibility that GOP senators could limit defections enough to keep the disapproval resolution from passing altogether.

That outcome is now almost certainly out of reach.

“There was an effort, numerous efforts, to engage with the vice president and the president,” said Sen. John Cornyn (R-Tex.). But “the president is not persuaded.

“I don’t know of any president that likes to give up power,” Cornyn added.

Trump called Lee to express his opposition as Lee lunched with fellow Republican senators at the Capitol, according to a person familiar with the call who spoke on the condition of anonymity to describe it. Lee then relayed the information to his colleagues.

Trump has been warning GOP senators against crossing him on the national emergency. Speaking Wednesday at the White House, he said it would be “a bad thing” to vote against the declaration.

“We’ll see whether or not I have to do the veto,” Trump said.

“It will be, I think, all very successful, regardless of how it all works out,” Trump said of his border effort. “A lot of money’s being spent right now. We have access to a lot of money, and more money is coming in, and people are starting to see it.”

Trump also expressed his frustration with the GOP in a tweet on Wednesday.

“Republican Senators are overthinking tomorrow’s vote on National Emergency. It is very simply Border Security/No Crime — Should not be thought of any other way. We have a MAJOR NATIONAL EMERGENCY at our Border and the People of our Country know it very well!” Trump tweeted.

The other GOP senators who plan to support the disapproval resolution are Susan Collins (Maine), Lisa Murkowski (Alaska) and Rand Paul (Ky.).

Several others remain undecided or undeclared. One of those, Sen. Lamar Alexander (R-Tenn.) attending a White House meeting with other GOP lawmakers Wednesday focused on trade. Trump lobbied him against the disapproval resolution, but Alexander said the pressure was not overly aggressive.

“I appreciate the way he handled the meeting,” Alexander said. Asked whether he has made a decision, Alexander said: “I certainly will by tomorrow.”

Many Senate Republicans had started to align behind Lee’s measure, which would amend the National Emergencies Act to say an emergency declaration would automatically expire after 30 days unless both chambers of Congress vote to keep it. The goal is to give Congress the authority to approve a national emergency declaration — not to disapprove it, as is currently the case in law.

If it had become law, Lee’s bill could have affected Trump’s national border emergency in the future, since ongoing national emergency declarations must be reaffirmed annually. And it would have affected future national emergencies declared by Trump, as well as by other presidents.

But even before Trump announced his opposition, Lee’s bill had run into obstacles. Earlier Wednesday, House Speaker Nancy Pelosi (D-Calif.) said that her chamber would not take it up, characterizing it as an attempt to give Trump “a pass” on violating the Constitution.

In remarks on the Senate floor on Wednesday, Senate Minority Leader Charles E. Schumer (D-N.Y.) called the measure crafted by Lee a “fig leaf.”

“Our Republican friends are saying with this fig leaf, ‘Grant me the courage to stand up to President Trump, but not yet,’ ” Schumer said. “And next time and next time and next time, they’ll say the same thing. So let’s do the right thing. Let’s tell the president he cannot use his overreaching power to declare an emergency when he couldn’t get Congress to do what he wanted.”

Paul Kane and Mike DeBonis contributed to this report.