A group of Senate Republicans is set to join with their Democratic colleagues on Wednesday to pass a resolution that would eliminate President Trump’s new tariffs on Canada. While the resolution would likely not be taken up in the House by Speaker Johnson, the fact that such a rebuke of Mr. Trump could come from the Senate chamber, where Republicans hold a majority of the 53 seats, would be an embarrassment to the president. 

Mr. Trump’s hostility toward the Canadians started in earnest while he was president-elect, when he threatened Canada with a 25 percent blanket tariff unless they cracked down on illegal immigration through America’s northern border and stopped the flow of fentanyl, despite the fact that just one percent of fentanyl seized by Customs and Border Patrol last year came via Canada.

Mr. Trump’s subsequent demand that Canada become the 51st state has roiled the country’s domestic politics and led to a nearly universal condemnation of the American government by Canadian officials. 

Senators in key states now say that the tariffs on Canada — America’s largest trading partner — need to be stopped before they irreparably harm the longstanding friendship. 

The resolution, introduced by Senator Kaine, would revoke Mr. Trump’s declaration of a national emergency for the northern border, a move that would then prevent the president from being able to impose tariffs on Canadian goods. 

In a Truth Social post on Tuesday night, Mr. Trump attacked Mr. Kaine for the resolution and called on Republicans to block it. 

“Senator Tim Kaine, who ran against me with Crooked Hillary in 2016, is trying to halt our critical Tariffs on deadly Fentanyl coming in from Canada. We are making progress to end this terrible Fentanyl Crisis, but Republicans in the Senate MUST vote to keep the National Emergency in place,” the president wrote. “By their weakness, the Democrats have allowed Fentanyl to get out of hand. The Republicans and I have reversed that course, strongly and quickly.”

Mr. Trump’s demands did not stop a number of GOP lawmakers from coming out in support of Mr. Kaine’s resolution. 

“The Maine economy is integrated with Canada — our most important trading partner from home heating oil, gasoline, jet fuel, and other refined petroleum products,” Senator Collins said in a speech on the Senate floor Wednesday. “The tariffs on Canada would be detrimental to many Maine families and our local economies.”

Senator McConnell — arguably Mr. Trump’s last great nemesis still working in Republican politics — also said he would back Mr. Kaine’s resolution to stop the Canadian tariffs ahead of Mr. Trump’s “Liberation Day” event on Wednesday. According to NBC News, Mr. McConnell privately told Mr. Kaine on Tuesday night that he will vote yes for his proposal when it comes up for a vote on Wednesday night. 

The president went on another tirade against the Republican senators leaning toward voting for Mr. Kaine’s resolution early Wednesday morning. Mr. Trump called out four specific senators — Ms. Collins, Mr. McConnell, Senator Murkowski, and Senator Paul — to say they were “playing with the lives of the American people, and right into the hands of the Radical Left Democrats and Drug Cartels.” 

The president bizarrely added that by supporting Mr. Kaine’s resolution, Republicans would be taking away his ability to place tariffs on “this horrible and deadly drug in order to make it more costly to distribute and buy,” even though the illegal drug market is not subject to customs. 

“The Senate Bill is just a ploy of the Dems to show and expose the weakness of certain Republicans, namely these four, in that it is not going anywhere because the House will never approve it and I, as your President, will never sign it,” Mr. Trump wrote. 

“Why are they allowing Fentanyl to pour into our Country unchecked, and without penalty. What is wrong with them, other than suffering from Trump Derangement Syndrome, commonly known as TDS? Who can want this to happen to our beautiful families, and why?” he asked. Mr. Trump further described the four lawmakers as “extremely difficult to deal with and unbelievably disloyal to hardworking Majority Leader John Thune, and the Republican Party itself.”

Kentucky’s two senators, Messrs. McConnell and Paul, rarely agree on anything, though on the tariff issue they are in lock-step. Both men have described tariffs as taxes on American consumers that can be capriciously handed down by the executive. 

“Tariffs are bad for our country, bad for prosperity, bad for the economy. And rule by emergency would be contrary to the concept of having representatives in Congress,” Mr. Paul told reporters on Tuesday.