The Republican establishment is revolting against President Donald Trump’s threat to impose tariffs on Mexico in retaliation for immigrants crossing the southern border.

“I think it was a mistake,” Sen. John Kennedy (R-LA) said in an interview Sunday, adding: “I don’t think the President is going to impose these tariffs […] He’s been known to play with fire, but not live hand grenades. And if he slaps a 25% tariff on Mexico, it’s going to tank the American economy. I think the President knows that.”

Trump, who’s said he would exercise his authority under the International Emergency Economic Powers Act to implement the tariffs, has threatened a tariff on Mexican imports beginning at 5% on June 10 and increasing 5% monthly up to 25%, “until such time as illegal migrants coming through Mexico, and into our Country, STOP,” he tweeted Thursday.

The President soon confused his message, tweeting about drugs coming across the border and falsely saying the United States has “a 100 Billion Dollars Trade Deficit with Mexico.” The bluster recalled a similar stance from Trump just two months ago, when the President threatened to completely shut down the U.S.-Mexican border, then ultimately did not do so.

Republicans in Congress, typically wary of crossing the President, spoke out.

Sen. Joni Ernst (R-IA) said “this isn’t the right path forward.” Fellow Iowan Sen. Chuck Grassley (R-IA) called it “a misuse of presidential tariff authority and counter to congressional intent” and urged “the president to consider other options.” Sen. Pat Toomey (R-PA) said “a blanket tax increase on everything Americans purchase from Mexico” was “the wrong remedy” and that Congress should “reassert its Constitutional responsibility on tariffs.” A spokesperson for Sen. John Cornyn (R-TX) said he “opposes this across-the-board tariff which will disproportionately hurt Texas.”

Sen. Rob Portman (R-OH), like many others, noted the damage the tariffs could do to Trump’s still-unratified update to NAFTA, the United States-Mexico-Canada Trade Agreement (USMCA).

Bloomberg News’ Steven Dennis catalogued’ Republicans’ feelings on the threatened tariffs with one emoji each, mostly downturned thumbs.

The White House didn’t bother to give federal agencies or business groups a heads up about the tariff threat, NBC News reported Friday, citing an unnamed senior administration official and two unnamed sources “familiar” with the situation. Nor were congressional committees notified, another unnamed source said. One administration source described the situation to NBC as “flying blind.”

The announcement of scheduled tariffs came hours before U.S. Trade Representative Robert Lighthizer, who reportedly opposes the tariffs, sent a letter to Congress in yet another (now even more unlikely) bid to pass Trump’s proposed USMCA.

Perhaps it’s no surprise, then, that not even the senior Trump administration officials who should have the most knowledge about the tariff threat didn’t defend it very well in the days that followed.

“The Mexican government has plenty of time to begin to work with us on these, um, measures,” White House trade adviser Peter Navarro said Friday, calling Trump’s threatened tariffs “smart.” On Sunday, Acting Homeland Security Secretary Kevin McAleenan couldn’t explain how applying the tariffs would do anything to stem the flow of migrants and asylum seekers rather than increasing numbers as Mexico feels the economic impact.

And on Monday, top White House economic adviser Kevin Hassett had to assure CNBC that the tariffs weren’t the basis for his resignation, which Trump had announced Sunday.

Without saying so himself, Hassett indicated he didn’t think Trump would follow through on the tariffs.

“If you look at currency movements and tariffs, you can model what the market thinks,” he said. “The market definitely doesn’t think that it’s guaranteed they’re going on right now.”

But if imported Mexican goods were ultimately hit, he said on CNN Monday, Americans would feel it.

“If we got to 25% tariffs, there would be costs to that, for sure,” he said.

Corporate groups that have cheered Trump’s tax cuts and deregulation also drew a line in the sand. The Chamber of Commerce is considering legal action, its executive vice president said.

The Heritage Foundation felt similarly, as did the National Association of Manufacturers. The group’s president and CEO, Jay Timmons, said “intertwining” immigration and trade objections with tariffs “creates a Molotov cocktail of policy.”

Economist Matthew Slaughter, who served on former President George W. Bush’s Council of Economic Advisers, told the Washington Post bluntly: “Starting to levy tariffs on Mexico is like levying tariffs on Texas.”

On Monday, Commerce Secretary Wilbur Ross will meet with his Mexican counterpart, Mexican Economy Minister Graciela Marquez. On Wednesday, U.S. Secretary of State Mike Pompeo will meet with Mexican Foreign Minister Marcelo Ebrard, Ebrard tweeted.

Trump, making final preparations for a trip to Europe Sunday, didn’t offer much help.