Senate Republicans on Tuesday said the Trump administration is now considering another national emergency declaration in order to institute proposed tariffs on Mexico over the southern border crisis, setting up another fight within his own party.

According to a report from The Hill, Senate Republicans met with White House officials and said the issue was discussed, but there is no decision as of yet on whether the step is necessary.

“I think that was somewhat up in the air. … I think that’s a distinct possibility but I don’t think there’s any definitive answer,” Sen. Ron Johnson, R-Wisc., told reporters.

“The way they put it was, they’re still working through all the details on it and they have not decided what their approach is going to be yet with regard to that. That was my understanding,” Sen. Mike Rounds, R-S.D., said.

Trump says he will impose the tariffs under the same 1977 International Emergency Economic Powers Act he used to divert funding to his border wall project. The Trump administration scored a big victory earlier this week when a judge ruled House Democrats couldn’t legally sue the White House on this issue.

The important details over a second national emergency declaration would set up a fight among Senate Republicans who are publicly and privately in opposition to the tariffs, which are effectively a tax on U.S. citizens and businesses, and Trump’s M.O. when trying to get his way on something.

The emergency declaration would set up another vote in an attempt to block the tariffs from going into effect.

“Within our own groups I think we recognize that we may very well have another vote coming up,” Rounds said.

The Senate passed a resolution of disapproval to block the emergency declaration earlier this year, which was then overruled with a presidential veto. Congress then didn’t have the two-thirds super majority to overrule the veto.

This time it could.

Senate Majority Leader Mitch McConnell said Tuesday there is “not much support” for tariffs on Mexico, and Tuesday’s meeting reportedly got heated at times with roughly a half-dozen senators speaking out, none in favor of the tariffs. The senators reportedly warned administration officials that they better count the votes before moving on with an emergency declaration because the White House could fall short on vetoing the resolution of disapproval this time.

“Deep concern and resistance,” is how Sen. Ted Cruz of Texas characterized the mood. “I will yield to nobody in passion and seriousness and commitment to securing the border, but there’s no reason for Texas farmers and ranchers and manufacturers and small businesses to pay the price of massive new taxes.”

Trump offered mixed messages at a London press conference.

“We’re going to see if we can do something,” he said on the second day of his state visit to Britain. “But I think it’s more likely that the tariffs go on.

He also said he doubted Republicans in Congress would muster the votes against him.

“If they do, it’s foolish,” he said.

He also tweeted a quote from House Minority Leader Kevin McCarthy, R-Calif., early Wednesday morning, saying House Republicans support the tariffs.

The Associated Press contributed to this report.