Donald Trump has made light of the impending vote on his impeachment at a public rally.
Addressing a cheering crowd of his supporters in Michigan, the US leader said it "doesn't really feel like we're being impeached".
"The country is doing better than ever before," he said to thunderous applause. "We did nothing wrong and we have tremendous support in the Republican Party, like we've never had before."
The first article of impeachment against Mr Trump — for abuse of power — passed at 8.23pm eastern time (12.23pm AEST) with the 216 votes needed to push it through.
Mr Trump was charged with two articles of impeachment including "abuse of power" which relates to claims that he pressured the president of Ukraine to investigate a Democratic rival and withheld crucial US security aid.
The second charge of "obstruction of Congress" is related to allegations he stonewalled investigative efforts. Impeachment is an extraordinary check on presidential power spelled out in the US Constitution enabling congress to remove presidents who commit "high crimes and misdemeanours".
SUCH ATROCIOUS LIES BY THE RADICAL LEFT, DO NOTHING DEMOCRATS. THIS IS AN ASSAULT ON AMERICA, AND AN ASSAULT ON THE REPUBLICAN PARTY!!!!
Tens of thousands of Americans marched in support of impeachment last night, from a demonstration through a rainy Times Square in New York City to handfuls of activists standing vigil in small towns across the country.
Glenn Conway, of Holly Springs, North Carolina, attended his first political rally in 30 years.
"I think we have a president at this point who believes he's above the law," the 62-year-old said.
Mr Trump, who is the third US president to be impeached, slammed today's proceedings on Twitter, calling them "atrocious lies by the radical left".
House Speaker Nancy Pelosi opened the debate by declaring that Mr Trump had left the Democrats "no choice" other than to proceed with impeachment.
"If we do not act now, we would be derelict in our duty," Ms Pelosi said. "It is tragic that the President's reckless actions make impeachment necessary."