Factbox: Trump impeachment - What happens next?

(Reuters) - Republican Donald Trump is likely this week to become the third U.S. president to be impeached when the Democratic-led House of Representatives votes on charges stemming from his effort to pressure Ukraine to investigate political rival Joe Biden.

Here is what likely will happen:

Tuesday, Dec. 17

The House Rules Committee will determine issues such as the length of debate in the chamber and when to vote on impeachment.

Wednesday, Dec. 18

The full House is expected to vote on this day to impeach Trump. The vote is expected to fall largely along party lines. Some Democrats likely will defect, but not enough to endanger passage of the two articles of impeachment. Trump would remain in office pending the outcome of the Senate trial.

If impeachment is approved, the House would select lawmakers known as managers to present the case against Trump at a Senate trial. House Democrats say most of the managers are likely to come from the Judiciary Committee, and possibly from the Intelligence Committee that led the investigation. Many lawmakers hope to be selected for the high-profile job.

Early January

Trump would face a trial in the Senate to determine whether he should be convicted and removed from office. Senate Majority Leader Mitch McConnell, a Republican, expects to begin the trial in early January. The Senate is controlled by Trump’s fellow Republicans, who have largely defended the president. A two-thirds majority of those present and voting in the 100-member chamber would be needed to convict. That would probably require 20 of the chamber’s 53 Republicans to vote for conviction.

U.S. Chief Justice John Roberts would preside over the trial. House managers would present their case against Trump and the president’s legal team would respond, with the senators acting as jurors. A trial could involve testimony from witnesses and a grueling schedule in which proceedings occur six days a week for as many as six weeks.

McConnell has said the Senate could go with a shorter option by voting on the articles of impeachment after opening arguments, skipping the witnesses. But McConnell is still conferring with the White House on that.

Reporting by David Morgan; Editing by Andy Sullivan, Alistair Bell and Peter Cooney