The House of Representatives impeached President Donald Trump on Dec. 18 on two charges: abuse of power and obstruction of Congress.
It's now up to a trial in the Senate to determine if those charges - officially called articles - merit removing Trump from the presidency.
The ceremonial start to the third trial of a sitting president began Thursday. Presidents Andrew Johnson and Bill Clinton were tried and acquitted by the Senate in 1868 and 1993, respectively.
The trial resumes Tuesday with senators debating rules for how the trial will be conducted, and the start of opening arguments from House managers and White House lawyers.
Here's a look at how the process will unfold:
What's already happened
Seven House lawmakers, who are called "managers" will prosecute the case against Trump. They brought the articles of impeachment to the full Senate on Jan. 16 and read the charges aloud. From left to right: Adam Schiff, Zoe Lofgren, Jerrold Nadler, Jason Crow, Val Demings, Sylvia Garcia, Hakeem Jeffries.
Supreme Court Chief Justice John Roberts was sworn in and will preside over the the trial.
"I do," the members of the full Senate affirmed to an oath read by Roberts.
The trial begins
Senate Majority Leader Mitch McConnell will reopen the trial at 1 p.m. on Tuesday. The first order of business will likely be to set the rules of the trial. Key questions will be:
How many hours does each side have to make their case?
Will additional witnesses be allowed?
A 51-vote majority will decide the rules, so the 53-Republican majority could control the direction of the trial.
House managers present case
Trump is accused of soliciting foreign interference in the 2020 election by asking Ukraine to investigate his political rival. During a July 25 phone call, Trump urged Ukrainian President Volodymyr Zelensky to investigate former Vice President Joe Biden, whose son Hunter once sat on the board of a Ukrainian energy company.
Trump attorneys present defense
From left to right: Pat Cippilone, Jay Sekulow, Alan Dershowitz, Ken Starr, Robert Ray, Pam Bondi, Patrick Philbin, not pictured: Michael Purpura and Jane Raskin. More on Trump's team.
President Trump's defense is unclear. The White House didn't participate in the House hearings, forbidding staffers from testifying. Regardless, Trump has said he did nothing improper and has called the impeachment inquiry a "hoax."
Senators are not allowed to speak during the trial. After the two sides make their arguments, senators will likely be able to ask questions in writing, which Roberts would read.
The House managers and Trump's defense present closing arguments.
Decision time for senators
The senators could call for closed session to discuss the evidence or discuss options such as censure that would leave Trump in office, but voice Congress' concerns with his actions.
The senators will vote on both articles of impeachment. A two-thirds majority of the Senate would be required to convict and remove Trump, which is unlikely in the chamber where Republicans outnumber Democrats 53 to 47.
Photos by AP, Getty Images, Joyce Naltchayan/AFP via Getty Images and William Pratt, U.S. Army.
This article originally appeared on USA TODAY: Trump impeachment: What are the steps in the Senate trial