The Trump administration has indicated that it may declare a second national emergency in order to implement new tariffs announced on Mexico, according to Senate Republicans, who announced the potential plan following a closed-door lunch with White House deputy counsel Pat Philbin and DOJ officials.

There was no word on the likelihood of this happening, however on Sunday, acting White House chief of staff Mick Mulvaney said that President Trump "is absolutely, deadly serious" about the tariffs, adding "I fully expect these tariffs to go on to at least the 5% level on June 10. The president is deadly serious about fixing the situation at the southern border."

The White House announced Thursday that the import tax will increase by 5 percentage points every month through October, topping out at 25%, unless Mexico takes significant action to stem the flow of migrants, mostly from Central America, who have surged to the U.S. border in recent months. -LA Times

As far as declaring a national emergency to enact the tariffs, "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," said Sen. Ron Johnson (R-WI) following the lunch.

Sen. Mike Rounds (R-SD) said that the administration is still "working through" whether it would even need to declare the national emergency in the first place, a move which would set up yet another clash with Congressional Democrats and Republicans opposed to the idea.

"Tariffs are not real popular in the Republican conference," said Johnson.

"The way they put it was is 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," said Rounds.

Trump says he will impose the tariffs on Mexico under the 1977 International Emergency Economic Powers Act as soon as next week unless Mexico cracks down on the flow of migrants from Central America across the southern border. But declaring a second national emergency, after Trump used the tool earlier this year to sidestep Congress on border funding, would pave the way for a significant fight with Senate Republicans, who have publicly and privately voiced opposition to the tariffs. A new national emergency declaration, GOP senators say, would set up a new resolution of disapproval vote in an attempt to block the tariffs from going into effect. -The Hill

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

Earlier this year, the Senate passed a resolution disapproving of Trump's emergency declaration along the US-Mexico border. Trump vetoed the measure and Congress could not override him. Senate GOP are mulling a similar resolution of disapproval if Trump once again declares a national emergency to implement the tariffs.

According to Senate Majority Leader Mitch McConnell (R-KY), there was "not much support" for the tariffs within the caucus.

Trump administration officials received an earful from senators during the closed-door GOP lunch, according to senators who attended the lunch. Sen. Ted Cruz (R-Texas) said that there was "deep concern" within the meeting about the prospects of new tariffs against Mexico. A GOP senator who attended the meeting said that roughly a half dozen senators spoke during the closed-door lunch, none of whom were supportive of new tariffs against Mexico. The senator added that administration officials were warned during the lunch that they needed to count the votes on a potential resolution of disapproval because Trump could fall short. -The Hill

"I think it's fair to say … that every senator who spoke, and there were probably a half dozen, generally had the same point of view," said the GOP senator cited by The Hill. "Nobody was supportive, who spoke."