U.S. President Donald Trump took to Twitter to ask his millions of followers to say a prayer, as the House of Representatives was readying to impeach a president for only the third time in the country’s history.

“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.

This should never happen to another President again. Say a PRAYER!” Mr Trump posted.

The president was also rapidly retweeting supporters in the conservative media and quoted a leading Republican in Congress who denounced the impeachment process and slammed Trump’s opponents as people who “all they had was never to let him have an easy breath.”

Similarly, Mr Trump is “frustrated” by the impeachment process against him, White House spokeswoman Stephanie Grisham told Fox news.

“He’s frustrated, as evidenced by the letter yesterday,” she said, referring to a seething six page letter sent by Mr Trump to Speaker of the House Nancy Pelosi in which he accused is opponents of waging open war and seeking to overthrow democracy.

“At the end of the day he did nothing wrong,” she said. She insisted he remained “focused” on his job as president.

The U.S. House of Representatives is expected to vote on Wednesday to impeach Mr Trump for obstruction of Congress and abuse of power related to his dealings with Ukraine.

If the articles of impeachment are approved, as expected, Mr Trump would become only the third U.S. president to be impeached.

No U.S. 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 along party lines.

Democrats control the House 233 to 197 seats over Republicans, with one independent and four vacancies.

The impeachment process has deepened political divides in the U.S. 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 Ms Pelosi on Tuesday, Mr 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,” Mr 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,” Mr Trump wrote.