House Republican leaders on Tuesday quietly moved to shield their members from having to vote on whether to end President Trump’s tariffs on Mexico, Canada and China, tucking language into a procedural measure that effectively removed their chamber’s ability to undo the levies.

The maneuver was a tacit acknowledgment of how politically toxic the issue had become for their party, and another example of how the all-Republican Congress is ceding its power to the executive branch.

In this case, Republican leaders did so using a particularly unusual contortion: They essentially declared the rest of the year one long day, nullifying a law that allows the House and Senate to jointly put an end to a disaster declared by the president.

House Democrats had planned to force a vote on resolutions to end the tariffs on Mexico and Canada, a move allowed under the National Emergencies Act, which provides a mechanism for Congress to terminate an emergency like the one Mr. Trump declared when he imposed the tariffs on Feb. 1.

That would have forced Republicans — many of whom are opposed to tariffs as a matter of principle — to go on the record on the issue at a time when Mr. Trump’s commitment to tariffs has spooked the financial markets and spiked concerns of reigniting inflation.