Democrats have unveiled formal charges against President Donald Trump on Tuesday accusing him of abusing power and obstructing Congress, making him only the third US president in history to face impeachment.
The full House of Representatives is expected to vote on the charges, or articles of impeachment, next week.
The chamber, controlled by Democrats, is almost certain to vote to impeach the Republican president, setting the stage for a dramatic trial in the Republican-controlled Senate, likely to begin in January.
House Judiciary Committee chairman, Jerrold Nadler, told reporters that Trump had endangered the US Constitution, undermined the integrity of the 2020 election and jeopardized national security.
"No one, not even the president, is above the law," Nadler said.
Speaker of the House Nancy Pelosi said Trump had "corrupted our democracy".
Trump has denied wrongdoing and calls the inquiry a hoax.
The White House has refused to participate in the hearings in the House because it says the process is unfair.
Trump took to Twitter early on Tuesday to attack the impeachment proceedings, calling it "sheer Political Madness".
Democrats have moved rapidly in their impeachment inquiry since launching an investigation on Sept. 24 into allegations that Trump pressured Ukraine to investigate a Democratic political rival, former Vice President Joe Biden, in the 2020 elections.
Democrats accuse Trump of abusing power by withholding aid to Ukraine, a vulnerable U.S. ally facing Russian aggression, as well as dangling a possible White House meeting to get Ukrainian President Volodymyr Zelenskiy to launch the investigation.
Republicans accuse Democrats of seeking to overturn the results of the 2016 election with a "witch hunt" against Trump, who denies he did anything wrong. Trump is unlikely to be convicted in the Senate, given it is controlled by his party, but his impeachment may yet have an impact on the campaign trail as Democrats seek to retake control of the White House.