Democrats have announced two articles of impeachment charging Donald Trump with abuse of power and obstruction of Congress.
The charges stem from the president’s pressure on Ukraine to announce investigations into his political rivals as he withheld aid to the country.
Earlier on Tuesday, Mr Trump tweeted he did “NOTHING” wrong and that impeaching a president with his record would be “sheer Political Madness!”
House of Representatives speaker Nancy Pelosi said ahead of the announcement that Mr Trump tried to “corrupt our upcoming elections” and remains a “threat to our democracy and national security”.
She said the House was taking next steps to “defend the democracy”.
US secretary of state Mike Pompeo has claimed Democrats are trying to “intimidate and bully” five current and former career officials in demanding depositions on dealings with Ukraine.
Mr Pompeo said in a letter to the House Foreign Affairs Committee, as part of the chamber’s impeachment inquiry into President Donald Trump, that the requested dates for the officials to voluntarily appear are “not feasible”.
“I am concerned with aspects of your request,” Mr Pompeo wrote to Eliot Engel, chairman of the panel.
“I will not tolerate such tactics, and I will use all means at my disposal to prevent and expose any attempts to intimidate the dedicated professionals.”