There’s an element of plausibility here, given the hyperpartisan fervor that’s gripped American politics. But in the ensuing environment, Republicans seem to be saying that even the most outlandish accusations against a president — such as those hurled at President Biden by Representative Marjorie Taylor Greene, a Republican of Georgia in her first days in Congress — should be treated the same as what Democrats impeached Mr. Trump over.

In a broader sense, officials of both parties have suggested that regular impeachments may just become one of several regular features of a new and bitter normal in our politics. Previously rare or unthinkable measures could simply start happening all the time

Democrats argue that, in fact, Republicans have opened several Pandora’s boxes in recent years. They have taken unprecedented actions, led by Mr. Trump, that have abused certain norms to a degree that has destabilized a set of once-reliable government traditions. Senate Republicans’ blockade of President Barack Obama’s nomination of Judge Merrick B. Garland to the Supreme Court in 2016, for instance, cast doubt on any future president’s ability to fill a Supreme Court vacancy when the opposing party controlled the Senate.