Tierney Sneed contributed reporting.

Senate Majority Leader Mitch McConnell (R-KY) made it clear on Tuesday that he’s not going to bend over backwards to try to help President Trump protect his border wall emergency declaration.

McConnell said he hasn’t “reached a total conclusion” about whether Trump’s emergency declaration was legal, wouldn’t predict whether the GOP-controlled Senate would block an impending resolution aimed at undoing the declaration, and dodged a question about whether he plans to push other GOP senators to vote with Trump during a Tuesday afternoon press conference.

The House is expected to pass the resolution to rebuke Trump’s attempt to seize money for border wall construction on Tuesday evening, and it looks increasingly likely the Senate will follow suit.

McConnell’s reticence on the highly charged issue came as internal GOP opposition to Trump’s wall continued to build, with three GOP senators publicly saying they plan to vote with Democrats and against the President on the declaration and many more refusing to say whether or not they’ll stand with the president.

Republicans’ frustrations were aired during a closed-door lunch meeting between GOP senators and Vice President Mike Pence on Tuesday, where according to those present, a number of senators spoke up in opposition to the move.

Pence attended with two Trump administration lawyers who came to answer technical questions about the emergency declaration, and lawmakers peppered them with questions.

Sen. John Cornyn (R-TX), who had previously expressed concerns about the border wall declaration, said Tuesday that he personally plans to vote with Trump on the issue as he entered the luncheon. But he said he expected McConnell to let members “vote their conscience” on the resolution. And a few Republicans are already signaling their willing to buck Trump.

Sens. Lisa Murkowski (R-AK), Susan Collins (R-ME) and Thom Tillis (R-NC) all reiterated their plans to vote to undo the emergency declaration to reporters as they entered and left the meeting. That leaves Democrats just one vote short of passing the resolution. Many other Republicans made it clear Tuesday they weren’t ruling it out either, with a handful sending signals that they’re likely to vote with Democrats.

Sens. Lamar Alexander (R-TN) and Rand Paul (R-KY) both said they needed to see the language of the resolution itself — but both suggested they were leaning towards bucking their president.

“I am still looking at all the details, but I’m against running government by emergency,” Paul told reporters after the luncheon.

“I will decide when I am presented with what I am going to vote on. I haven’t changed my mind: It’s unnecessary, unwise and inconsistent with [the] U.S. constitution,” Alexander told reporters before the meeting. “When I see what I am asked to vote on, I will make a decision about how to vote.”

A number of other typically loyal GOP lawmakers also refused to rule out bucking Trump on the vote.

Sen. Pat Toomey (R-PA) said he was “still considering” whether or not to back the resolution after telling TPM he was “concerned” with Trump’s move. Sen. Jerry Moran (R-KS) said he hadn’t “made a decision” and has “a lot more to know” before making one. Sen. Pat Roberts (R-KS) said he’d yet to “take a hard look at this” but added that it will “be a tough vote.”

The vote appears like it will be largely symbolic. Trump’s actions have already been tied up in the courts, where they’ll likely be decided. The President has also said he’ll veto any measure looking to undo his emergency declaration, and while it looks like this will pass Congress, it does not appear it will gain quite enough support to override a veto.

“Probably all members are going to believe that this is going to be determined by a court, no matter what the Congress does,” Sen. Roy Blunt (R-MO) told reporters.

But Congress passing a resolution to undo Trump’s emergency declaration with strong bipartisan support would be an embarrassing rejection for the President from his own party, and the most high-profile vote so far where a number of Republicans split with their president.

McConnell reportedly warned Trump against making an emergency declaration before he did so in early February. The Senate leader advised Trump that it would split the GOP and that a resolution to undo it could pass Congress and force Trump into an embarrassing veto. It appears McConnell was correct.

This story was updated at 3:30 p.m. ET.