(Reuters) - The U.S. Senate expects to begin the trial of President Donald Trump in January if, as expected, the House of Representatives votes to impeach him this week.

FILE PHOTO: Chief Justice of the United States John G. Roberts is seen during a group portrait session for the new full court at the Supreme Court in Washington, U.S., November 30, 2018. REUTERS/Jim Young/File Photo

Here are the main players in what would be only the third such trial in U.S. history.

CHIEF JUSTICE JOHN ROBERTS

A conservative who was appointed by Republican President George W. Bush, Roberts might find himself celebrating his 65th birthday on Jan. 27 by presiding over Republican Trump’s impeachment trial.

Under the U.S. Constitution, the chief justice of the highest court is the referee in presidential impeachment trials.

Senateof lawyers arguing for his acquittal.

The White House has not yet announced who would spearhead this effort on the Senate floor.

White House counsel Pat Cipollone is expected to play a leading role, an administration official told Reuters. He has been working with deputies Patrick Philbin and Michael Purpura.

Cipollone, a 53-year-old Republican, sent an eight-page letter to Congress in October laying out why the White House was refusing to cooperate with the House inquiry, calling it a “charade.”

Trump lawyers are likely to argue that there is no evidence that the president did anything wrong and that the House investigation was partisan and flawed.

HOUSE ‘MANAGERS’

House Speaker Nancy Pelosi has not yet named the Democratic “managers” who would prosecute the case against Trump in the Senate. But some obvious potential choices