But whether they would or would not, many would argue that Democrats would still have a constitutional responsibility to exercise. Impeachment is the only remedy the founders provided for removing from office someone who is clearly unfit to hold it.

If all of what I stipulated above happens and the Democrats don’t act, aren’t they saying the Constitution is meaningless? If you can’t impeach a president whose very election is found to have been illegitimate, then whom can you impeach? And how do you recover, as a country, from such a bitterly partisan episode?

Those are good questions. But they have an obvious answer. While impeachment is clearly a valid exercise of power, so is another method of removal, also prescribed by the Constitution: an election. This is how Americans like to ditch presidents and parties they don’t like — presidential power has changed hands 44 times in this country’s history.

In addition, nine incumbent presidents have lost re-election, including three in the last half- century , and all have peacefully (if not always gracefully) yielded power. In contrast, only two presidents, Andrew Johnson and Bill Clinton, have been impeached by the House, though both were acquitted in the Senate. Richard Nixon, facing certain and imminent impeachment, resigned.

That’s a historical record that suggests that an electoral outcome will be much more widely accepted. Mr. Trump’s partisans will whine about the unfairness of it all in either case — they’ll blame “voter fraud,” or George Soros, or the “fake news media.” But if the voters have rebuffed the president, the whining will sound to most Americans like just that.

There’s one more reason I’d prefer to see Mr. Trump laid low via the ballot. It will do more long-term damage to the Republican Party.

If Mr. Trump is removed via impeachment and conviction — that is, with those 20 Republican votes — Republicans can say, “See, we’ve come to our senses; got that out of our system.” But if they renominate Mr. Trump and stick with him through November 2020 and the voters clearly say no, not again, Republicans are left sitting in the wreckage. They will be trying to air out the Trump stench for a generation, maybe two, which is precisely the fate they deserve.