President Donald Trump has been criticised for comparing the Democrats' impeachment inquiry to "a lynching."
House Speaker Nancy Pelosi opened the impeachment inquiry after a whistleblower's complaint that Mr Trump was attempting to use his office for personal political gain during a phone call with the Ukrainian president.
Lynchings, or hangings, historically were mostly used by white people against black men in the South beginning in the late 19th century amid rising racial tensions in the US.
By comparing the impeachment process to a lynching, Mr Trump was likening Democrats to a lynch mob.
The Republican president tweeted: "So some day, if a Democrat becomes President and the Republicans win the House, even by a tiny margin, they can impeach the President, without due process or fairness or any legal rights.
"All Republicans must remember what they are witnessing here - a lynching. But we will WIN!"
House Majority Whip Rep Jim Clyburn, the highest-ranking African American in Congress, criticised Mr Trump's word choices.
"That is one word no president ought to apply to himself," Mr Clyburn said on CNN after the president's tweet was read to him. "That is a word that we ought to be very, very careful about using."
Another black Democratic representative, Bobby Rush, called on Mr Trump to delete the tweet.
"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," wrote Mr Rush.
Mr Trump's tweet came a day after he lashed at critics of his decision - since rescinded - to schedule a major international economic summit for 2020 at one of his Florida golf properties. He lamented at one point during remarks Monday about "you people with this phoney emoluments clause."
The emoluments clause is in the Constitution and bans presidents from receiving gifts or payments from foreign governments.
A whistleblower's complaint that Mr Trump was attempting to use his office for personal political gain during a July 25 phone conversation with Ukraine's president led House speaker Nancy Pelosi to open the impeachment inquiry.
The president insists he did nothing wrong, characterising the conversation with Volodymyr Zelenskiy as "perfect" and arguing that Democrats are still trying to overturn the 2016 election that put him in the White House.
