Donald Trump made himself a political celebrity in 2016 by persuading news media to talk about — Donald Trump. He did it mainly by the expedient of saying outrageous things — by trolling, in the parlance of social media — and it worked.

On Tuesday the president guaranteed he’d be topic No. 1 for at least 24 hours by tweeting that the effort to impeach him is a “lynching.” Instantly, and perhaps as he intended, his critics in the media, on Capitol Hill and elsewhere expressed rage and disbelief that Trump could compare the conduct of his political opponents to the mobs that murdered African-Americans in an earlier, shameful era.

The verb to lynch means to execute without a trial or due process. It doesn’t refer only to extrajudicial killings in the post-Reconstruction and Jim Crow South. Accordingly, it’s occasionally used in a figurative sense in other English-speaking countries. But in the United States the word is electric for its historical context.

Clarence Thomas famously used it during his confirmation hearing in 1991 when, as he saw it, a cabal of white liberals sought to destroy his nomination to the U.S. Supreme Court by a “high-tech lynching.” Justice Thomas had what we would call political and historical standing.

But no president should use the word in the offhand and self-indulgent way that Trump did in his tweet. What’s so galling about this and similar pointless provocations is that, in his quest to remain always and forever in the headlines, Trump puts his more judicious allies on the political spot. Every Republican in Congress is immediately asked either to ignore him and risk association with his reckless pronouncements, or criticize him and risk his wrath.

Democrats are bent on impeaching Trump, and if he wants to survive he is going to need allies. The more he forces Republicans to defend words or actions that don’t deserve defending, the more their resentment will build and the more political trouble he will be in.