Republican senators sent the White House a sharp message on Tuesday, warning that they were almost uniformly opposed to President Trump’s plans to impose tariffs on Mexican imports, just hours after the president said lawmakers would be “foolish” to try to stop him.
Mr. Trump’s latest threat to impose 5 percent tariffs on all goods imported from Mexico, rising to as high as 25 percent until the Mexican government stems the flow of migrants, has prompted some of the most serious defiance in the Republican ranks since the president took office.
Republican senators emerged from a closed-door lunch at the Capitol angered by the briefing they received from a deputy White House counsel and an assistant attorney general on the legal basis for Mr. Trump to impose new tariffs by declaring a national emergency at the southern border.
“I want you to take a message back” to the White House, Senator Ted Cruz, Republican of Texas, told the lawyers, according to people familiar with the meeting. Mr. Cruz warned that “you didn’t hear a single yes” from the Republican conference. He called the proposed tariffs a $30 billion tax increase on Texans.
“I will yield to nobody in passion and seriousness and commitment for securing the border,” Mr. Cruz later told reporters. “But there’s no reason for Texas farmers and ranchers and manufacturers and small businesses to pay the price of massive new taxes.”
The president’s latest foray into a global trade war has troubled economists and roiled stock and bond markets. The Federal Reserve chairman, Jerome H. Powell, hinted on Tuesday that the central bank could cut interest rates if the trade war started to hurt the economy. The remarks sent stocks higher for their strongest day in months.
But senators were mindful of the long-term stakes for their home states.
Texas would be hit the hardest by the proposed tariffs on Mexican products, followed by Michigan, California, Illinois and Ohio, according to the U.S. Chamber of Commerce. A 25 percent tariff would threaten $26.75 billion of Texas imports.
Senator Kevin Cramer, Republican of North Dakota, expressed support for the president, as did Senator Thom Tillis of North Carolina, who is up for re-election in 2020 and faced blistering criticism after flip-flopping this year on whether he would vote to disapprove the president’s emergency declaration to build the wall.
“I think Mexico could help us solve the crisis down at the border,” Mr. Tillis told reporters. “What’s the tax on handling 80,000 additional illegal immigrants coming across the border, housing them, adjudicating them? You’ve got to look at the total cost of the prices.”
If a revolt comes to pass, it would start in the Senate, but House Republicans would have to join the effort to overturn a veto.
Representative Hakeem Jeffries of New York, the chairman of the House Democratic caucus, declined to forecast whether the House would try to block the tariffs on Mexico.
“The administration’s tariff policy is erratic and all over the place,” he said. “We will see what the Senate Republicans ultimately decide to do, but we will certainly strongly consider proceeding in a way that is appropriate and consistent with our legislative powers.”
Mr. Trump seemed unimpressed when a reporter noted that Mexican officials said that they had increased the number of migrants they had apprehended coming into their country from elsewhere in Central America. He offered no specifics on what it would take to keep the tariffs from being imposed.
“Look, millions of people are flowing through Mexico,” Mr. Trump said. “That’s unacceptable.”