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 1999, 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: 
7 managers
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, Jerry Nadler, Jason Crow, Val Demings, Sylvia Garcia, Hakeem Jeffries.
Chief Justice
Supreme Court Chief Justice John Roberts was sworn in and will preside over the the trial.
The Senate
“I do,” the members of the full Senate affirmed to an oath read by Roberts.
Oath the 100 senators take
Do you solemnly swear that in all things appertaining to the trial of the impeachment of Donald John Trump, president of the United States now pending, you will do impartial justice according to the Constitution and laws, so help you God?
The trial begins
Senate Majority Leader Mitch McConnell, R-Ky., 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?
McConnell has proposed allocating 24 hours to each side to present their case over two session days for each side.
How long will senators have for questions?
McConnell has proposed 16 hours to pose written questions.
What about witnesses or documents? 
McConnell proposes four hours of debate over whether to subpoena witnesses or documents.
Rules decided
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 Cipollone, Jay Sekulow, Alan Dershowitz, Ken Starr, Robert Ray, Pam Bondi, Patrick Philbin, not pictured: Jane Raskin, Michael Purpura and Eric Herschmann. More on Trump’s team.
The president’s legal team said in brief filed Monday that the two articles of impeachment against Trump “do not identify any impeachable offense;” the House impeachment inquiry was “irredeemably flawed,” and there is “no evidence” to back the House impeachment claims.
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 votes
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.
The verdict
Photos by AP, Getty Images, Joyce Naltchayan/AFP via Getty Images and William Pratt, U.S. Army.