Trump would become just the third US president to be removed from office.
A debate has begun in Washington ahead of an historic vote tonight which could see Donald Trump removed from office.
The US president denies asking the Ukrainian government to investigate his political rival, Joe Biden, in return for military aid.
Democrats - who are in favour of his impeachment - will likely vote to put him on trial in the Senate - which is mostly Republican.
If the articles of impeachment are approved, as is expected, Trump would become only the third US president to be impeached. No US president has been removed from office via the impeachment process.
Democratic Speaker Nancy Pelosi has the majority she needs to approve the two pending articles of impeachment, members said on Tuesday. Wednesday's votes, which are set for sometime in the afternoon or early evening, are expected to play out largely among party lines.
The impeachment process has deepened political divides in the US as the country heads for the 2020 presidential election. Those divides were on further display on the eve of the House votes.
In a vitriolic six-page letter to Pelosi on Tuesday, Trump called the House's impeachment drive a "charade" and a "colossal injustice".
"You are turning a policy disagreement between two branches of government into an impeachable offence," Trump said in the letter.
"I have no doubt that the American people will hold you and the Democrats fully responsible in the upcoming 2020 election," Trump wrote.
