Trump has frequently parroted the phrase “witch hunt” and other politically explosive language to denigrate the work of former special counsel Robert Mueller and various oversight efforts scrutinizing his administration.

But the invocation of “lynching” to characterize a process explicitly sanctioned by the Constitution marked a new, racially insensitive show of malice by the president toward lawmakers seeking to remove him from office.

According to a digital archive of Trump's social media feed, he only posted the term on one other occasion, in a September 2015 quoted tweet praising conservative radio host Mark Levin.

Senate Majority Leader Mitch McConnell (R-Ky.), who typically abstains from criticizing the president, expressed his disapproval when asked by reporters Tuesday afternoon about Trump's message.

“Given the history of this in our country, I would not compare it to a lynching,” he said. “That was an unfortunate choice of words.”

Democrats, meanwhile, were much more forceful in their condemnations.

House Majority Whip Jim Clyburn (D-S.C.), the highest-ranking African American in Congress, told CNN that the three U.S. presidents who previously faced impeachment threats would not have likened their situations to lynchings.

“That is one word no president ought to imply on himself,” he said. “I’ve studied presidential history quite a bit, and I don’t know if we’ve ever seen anything quite like this. Andrew Johnson never would’ve described what was happening to him this way, and certainly Bill Clinton didn’t, nor did Nixon. This president is hopefully an anomaly.”

Clyburn added: “I’m a product of the South. I know the history of that word. That is a word that we ought to be very, very careful about using.”

Several other black lawmakers expressed similar indignation at Trump’s analogy.

“You think this impeachment is a LYNCHING? What the hell is wrong with you?” tweeted Rep. Bobby Rush (D-Ill.), a civil rights activist who co-founded the Illinois chapter of the Black Panther Party. “Do you know how many people who look like me have been lynched, since the inception of this country, by people who look like you. Delete this tweet.”

“I don't know how many times we have to say that the President is racist and unfit to serve,” Rep. Bennie Thompson (D-Miss.) wrote online.

And Rep. Karen Bass (D-Calif.), chairwoman of the Congressional Black Caucus, asked incredulously: “You are comparing a constitutional process to the PREVALENT and SYSTEMATIC brutal torture of people in THIS COUNTRY that looked like me?”

Throughout his 2016 campaign and continuing into his presidency, Trump has been accused of fostering racial animus and assailing his Democratic rivals with crass or outright racist insults.