Trump had earlier told US House of Representatives Nancy Pelosi in a letter that 'history will judge you harshly'.
As Democrats set to vote on impeaching the US president, Trump in a tweet said he has done nothing wrong, while adding that it was "terrible thing".
"Can you believe that I will be impeached today by the radical Left, do nothing Democrats, and I did nothing wrong! A terrible thing. Read the transcripts," Trump said, adding,"This should never happen to another President again."
Trump had earlier told US House of Representatives Nancy Pelosi in a letter that "history will judge you harshly." The US president accussed Pelosi of "declaring open war on American Democracy."
President Trump is only the third US leader to ever be impeached. The US president is accussed of forcing Ukraine into a probe into a main 2020 re-election rival, Joe Biden. The US president is also accused of obstructing Congress by refusing to cooperate with the impeachment investigation.
The two articles of impeachment will be voted by the Democrats today. It will then be presented to the Senate in January while the Democrats hold a majority in the House of Representatives, the Republicans are in majority in the Senate.
Richard Nixon had quit office before being impeached in 1974. In 1999, 45 Democratic Senators had stayed united against the 55 Republicans to block a two-thirds vote for conviction against Clinton.