US senators have been sworn in as jurors in Trump's impeachment trial

• Senators have been sworn in as jurors Tuesday for Trump's second impeachment trial.
• A summons will now be sent to Trump and he will be invited to respond in writing.
• Oral arguments will kick off the week of February 8.

Senators were sworn in on Tuesday as jurors in former President Donald Trump's second impeachment trial.

The House of Representatives impeached Trump earlier this month, charging him with "incitement of insurrection" related to the deadly Capitol siege on January 6. The House transmitted the article of impeachment against Trump to the Senate on Monday evening.

A formal summons will now be sent to Trump laying out the charge against him and inviting him to respond in writing.

Typically, a Senate trial kicks off quickly after articles of impeachment are submitted, but Senate Majority Leader Chuck Schumer and Minority Leader Mitch McConnell reached a deal last week to delay the start of Trump's trial until the week of February 8.

Lawmakers agreed that the timeline would give Democratic House impeachment managers, who will act as prosecutors in the trial, and the former president's legal defense team, enough time to prepare their arguments. It will also allow the Senate to confirm President Joe Biden's Cabinet picks and push forward on his legislative agenda and COVID-19 relief proposal.

The Constitution stipulates that the chief justice of the Supreme Court presides over the impeachment trial of a US President. But it does not say who presides over the trial of a former president, and a Senate source told NPR on Monday that the chamber's president pro tempore, Vermont Sen. Patrick Leahy, will oversee Trump's second impeachment trial.

To remove a federal official from office, two-thirds of the Senate must vote to convict. That's highly unlikely in this case, given that Democrats have a bare majority in the chamber - 50 seats plus Vice President Kamala Harris' tie-breaking vote - and would need at least 17 of their Republican colleagues to break ranks.

The GOP caucus, for its part, doesn't have much of an appetite to even hold an impeachment trial in the first place, let alone convict Trump, because Republicans say it would be unconstitutional to conduct a trial for someone who's already out of office. Some legal scholars agree, though most have dismissed that argument.

"That makes no sense at all," the Yale Law School professor Akhil Reed Amar told NPR, referring to the Republican argument. "You want to give someone a get-out-of-jail free card at the end of the administration so they can do anything they like and be immune from the high court of impeachment?"

There is also precedent for impeaching and trying to convict a former federal official after they've left office. And in Trump's case, many Democratic lawmakers say it's necessary to impeach and try the former president in hopes of barring him from ever running for public office again. The Senate can only vote to take such a step if it also votes to convict Trump after his trial.

Here's what comes next:

• February 2: Deadline for Trump to respond to the summons and for the House impeachment managers - who will act as prosecutors in his Senate trial - to submit a pretrial brief.
• February 8: Deadline for Trump to submit a pretrial brief and for House managers to respond to Trump's response to the summons.
• February 9: Deadline for House managers to submit a rebuttal to Trump's pretrial brief. Oral arguments begin after.