Senate Republicans are facing pressure Wednesday from President Donald Trump to oppose a Democratic resolution that would nullify the presidential emergency on fentanyl he is using to implement tariffs on Canada.

Just hours after Trump announced his plan for import taxes on a slew of international trading partners — his so-called “Liberation Day” — the Senate was expected to vote on a resolution that offers Republicans an off-ramp to the import taxes on Canada.

Although Trump's order spared for now Canadian imports from new taxes, the Senate resolution is a significant test for Republican loyalty to Trump's vision of remaking the U.S. economy by clamping down on free trade. Many economists are warning that the plan could cause an economic contraction, and GOP senators are already watching with unease as Trump upends U.S. standing with the rest of the world.