President Donald Trump expressed disbelief Wednesday hours before the House was set to formally impeach him for his conduct involving Ukraine.

"Can you believe that I will be impeached today by the Radical Left, Do Nothing Democrats, AND I DID NOTHING WRONG!" Trump wrote on Twitter.

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! — Donald J. Trump (@realDonaldTrump) December 18, 2019

SUCH ATROCIOUS LIES BY THE RADICAL LEFT, DO NOTHING DEMOCRATS. THIS IS AN ASSAULT ON AMERICA, AND AN ASSAULT ON THE REPUBLICAN PARTY!!!! — Donald J. Trump (@realDonaldTrump) December 18, 2019

The House is set to vote Wednesday on two articles of impeachment against Trump. One article charges Trump with abusing his power for pushing Ukraine to announce investigations into former Vice President Joe Biden, his son Hunter Biden and Democrats and for withholding nearly $400 million in military aid to the country as well as an official White House meeting with Zelenskiy as he pursued those probes. The other article charges Trump with obstruction of Congress for stonewalling impeachment investigators examining his conduct.

The House is expected to pass both articles.

In a rambling six-page letter to House Speaker Nancy Pelosi, D-Calif., on Tuesday, Trump said the effort to impeach him amounted to a declaration of "open war on American Democracy” where he had less due process than "those accused in the Salem Witch Trials."

Speaking to reporters in the Oval Office, Trump said he takes "zero" responsibility for impeachment — "to put it mildly."

As the House began debating ahead of the impeachment vote, Trump posted dozens of tweets and retweets. He wrote that Pelosi "will go down in history as worst Speaker."

"Already thrown out once!" he added.

The president retweeted a dozen posts from Trump-friendly legal analysts Gregg Jarrett of Fox News and Alan Dershowitz, a Harvard law professor. Both men have presented the president with favorable legal analysis.