(Reuters) - Donald Trump became the third president in U.S. history to be impeached when the House of Representatives formally charged him on Wednesday with abuse of power and obstruction of Congress.

The votes set up a trial in the Republican-controlled Senate, where lawmakers must decide whether to convict Trump and remove him from office.

Here is what could happen over the coming weeks:

Late December

The House must still name “managers” to prosecute the case against Trump before the Senate. But House Speaker Nancy Pelosi is holding off naming them until she gets a clearer idea of how Senate Majority Leader Mitch McConnell intends to conduct the trial, fearing he will protect Trump by cutting short the proceedings and then holding a vote to reject the charges.

Pelosi is trying to pressure McConnell into reaching a deal with Senate Democratic Leader Chuck Schumer, who wants a full-scale trial that includes witness testimony from top Trump aides. The ploy could add pressure on McConnell from Trump, who wants a speedy trial. But the Kentucky Republican has rejected Schumer’s proposal and declared an “impasse” in the negotiations.

McConnell and Schumer can still be expected to negotiate in private and through the news media in the coming days.

In the meantime, House Democrats are not likely to deliver the articles of impeachment, or formal charges, to the Senate until after Congress returns in early January from a two-week holiday. To do otherwise would require Pelosi to summon lawmakers back to Washington to adopt a resolution appointing the managers, a possibility viewed by senior aides as very remote.

A Senate trial cannot begin until the charges have been submitted to the chamber.

Early January

Barring unexpected developments, Trump will face a trial in the Senate to determine whether he should be convicted and ousted from office when Congress returns to Washington in early January.

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. Senators would act as jurors. A trial could involve testimony from witnesses and a grueling schedule in which proceedings occur six days a week unless senators approve taking both Saturdays and Sundays off.