Impeachment trial live updates: Historic impeachment trial of Trump begins in the Senate with House prosecutors reading charges against the president

Roberts will wear his regular robe, have an office in the Capitol and may have lunch at the Senate, if time permits.

In the very unlikely event that he has to miss an oral argument at the Supreme Court, Justice Clarence Thomas, the court’s longest-serving member, will preside. But Roberts would still participate in deciding all cases.

Roberts will be pulling double duty as he does his job at the Supreme Court and presides over the impeachment trial of Trump, and the court’s public information office on Thursday tried to answer some of the questions that reporters have about how he will multitask.

Assuming impeachment proceedings begin in the afternoon, the chief justice will hear arguments at the court in the morning and go to the Capitol afterward, as Chief Justice William H. Rehnquist did when he presided over the impeachment trial of President Bill Clinton. After Wednesday, the court is not scheduled to hold oral arguments until Feb. 24. That is a regularly scheduled break in the oral argument calendar.

Roberts received the formal request to preside over the trial at 9:30 a.m. Thursday from the secretary of the Senate, Julie E. Adams, and he will be in the Senate at 2 p.m. to take the oath and swear in senators. It is likely that he will make brief remarks, as Rehnquist did.

The chief justice is expected to use the ceremonial President’s Room as an office in the Capitol, the same space used by Rehnquist, and Roberts and his law clerks will conduct court work as they usually do, using computers and hard copies of briefs. He will be accompanied by his counselor, Jeffrey P. Minear, and one of his four law clerks will assist him throughout the trial.

And, also as Rehnquist did, Roberts will make the short trip across First Street from the Supreme Court to the Capitol by car.