WATCH: House To Debate And Vote On Articles Of Impeachment

On Wednesday, almost 21 years to the day since the House last debated impeaching a president, it does so again.

Lawmakers will take up two articles of impeachment against President Trump. They charge him with abusing his power and obstructing Congress. Each was approved on a party-line vote last week by the House Judiciary Committee, and Wednesday's vote is also expected to closely follow party lines.

Republicans have remained solidly behind the president, while Democrats — who control the House — have run the process leading up to Wednesday.

Lawmakers will convene at 9 a.m. ET before heading into six hours of debate, as determined by the House Rules Committee Tuesday night. After debate, they will vote on each article.

Trump on Tuesday released a scorching letter to House Speaker Nancy Pelosi, D-Calif., in which he called the impeachment effort an "illegal , partisan attempted coup."

He wrote, "You are unwilling and unable to accept the verdict issued at the ballot box during the great Election of 2016. So you have spent three straight years attempting to overturn the will of the American people and nullify their votes. You view democracy as your enemy!"

The president told reporters Tuesday that he takes "zero" responsibility for getting impeached.

Democrats charge that the president abused the power of his office "by ignoring national security and other vital national interests to obtain an improper personal political benefit," according to an impeachment report by House Democrats on the Judiciary Committee, released on Sunday. It further charges that Trump "betrayed the nation by abusing his high office to enlist a foreign power in corrupting democratic elections."

As to the second article, obstruction of Congress, the Judiciary Committee majority charges that "no president has ever claimed the unilateral prerogative to categorically and indiscriminately deny a House impeachment inquiry," and that Trump's "direction to defy House subpoenas constituted an assault on the Impeachment Clause itself."

Should the House approve either article, the scene will shift to the Senate for a trial, with all 100 senators acting as jurors. Two-thirds, or 67 votes, will be needed to convict Trump, an outcome that seems unlikely in the Republican-led Senate. In remarks to reporters on Tuesday, Senate Majority Leader Mitch McConnell, R-Ky., said he is not neutral on whether Trump should be removed from office.

"I'm not an impartial juror. This is a political process. There's not anything judicial about it. Impeachment is a political decision. The House made a partisan political decision to impeach. I would anticipate we will have a largely partisan outcome in the Senate. I'm not impartial about this at all," McConnell said.

Giving a taste of the continuing party battles, McConnell has rejected a Democratic proposal for certain witnesses. Senate Minority Leader Chuck Schumer, D-N.Y., called for White House chief of staff Mick Mulvaney and former national security adviser John Bolton to testify, along with two others. But McConnell rejected the idea, calling it "dead wrong."

Copyright 2019 NPR. To see more, visit https://www.npr.org.