We understand the argument that the best result would be for voters, rather than the Republican Party, to do the job of removing Mr. Trump. But we believe this argument neglects an important reason that Mr. Trump’s removal by his party would be at least as healthy, democratically speaking: It would reinvigorate the idea that political parties exist not just as vehicles for politicians but as protectors of vital democratic norms.

The most troubling — and from our point of view the most disappointing — development of the Trump era is not the president’s own election and subsequent behavior; it is the institutional corruption, weakness and self-betrayal of the Republican Party. The party has abandoned its core commitments to constitutional norms, to conservative principles and even to basic decency. It has allowed itself to be hijacked by a reality television star who is a pathological liar, emotionally unsteady and accountable only to himself. And it has embraced presidential conduct that, if engaged in by a Democrat, it would have been denounced as corrupt, incompetent and even treasonous.

We disagree with those who think that Mr. Trump’s removal by his own party would weaken democratic accountability; if anything, the opposite is true.