Donald Trump will make history as the first former president to stand trial on criminal charges when his hush money case opens Monday with jury selection.

The case will force the presumptive Republican presidential nominee to juggle campaigning with sitting in a Manhattan courtroom for weeks to defend himself against charges involving a scheme to bury allegations of marital infidelity that arose during his first White House campaign in 2016.

It carries enormous political ramifications as potentially the only one of four criminal cases against Trump that could reach a verdict before voters decide in November whether to send him back to the White House.

Here’s what to know about the hush money case and the charges against Trump:

WHAT’S THIS CASE ABOUT?

The former president is accused of falsifying internal Trump Organization records as part of a scheme to bury damaging stories that he feared could hurt his 2016 campaign, particularly as Trump’s reputation was suffering at the time from comments he had made about women.

The allegations focus on payoffs to two women, porn actor Stormy Daniels and Playboy model Karen McDougal, who said they had extramarital sexual encounters with Trump years earlier, as well as to a Trump Tower doorman who claimed to have a story about a child he alleged Trump had out of wedlock. Trump says none of these supposed sexual encounters occurred.

Trump’s former lawyer and fixer, Michael Cohen, paid Daniels $130,000 and arranged for the publisher of the National Enquirer supermarket tabloid to pay McDougal $150,000 in a journalistically dubious practice known as “catch-and-kill” in which a publication pays for exclusive rights to someone’s story with no intention of publishing it, either as a favor to a celebrity subject or to gain leverage over the person.

Prosecutors say Trump’s company reimbursed Cohen and paid him bonuses and extra payments, all of which were falsely logged in Trump Organization records as legal expenses. Cohen has separately pleaded guilty to violating federal campaign finance law in connection with the payments.

WHAT ARE THE CHARGES?

Trump is charged with 34 felony counts of falsifying business records. The charge carries up to four years in prison, though whether he will spend time behind bars if convicted would ultimately be up to the judge.

The counts are linked to a series of checks written to Cohen to reimburse him for his role in paying off Daniels. Those payments, made over 12 months, were recorded as legal expenses in various internal company records.

To win on the felony charge, prosecutors must show that Trump not only falsified or caused business records to be entered falsely — which would be a misdemeanor — but that he did so with intent to commit or conceal a second crime.

Manhattan District Attorney Alvin Bragg did not specify the other crime in Trump’s indictment, but has since said that evidence shows his actions were meant to conceal state and federal campaign finance and tax crimes. Some experts argue it’s an unusual legal strategy that could backfire.

HOW WILL JURY SELECTION WORK?

The process to choose 12 jurors, plus six alternates, will begin with Judge Juan M. Merchan bringing scores of people into his courtroom to begin weeding out people for potential biases or other reasons they cannot serve. The judge has said he will excuse anyone who indicates by a show of hands that they can’t serve or can’t be fair and impartial before calling groups of those who remain into the jury box to answer 42 questions. Potential jurors will be known only by number, as the judge has ordered their names to be kept secret from everyone except prosecutors, Trump and their legal teams.

Among the questions potential jurors will be asked: Whether they follow the former president on social media, have ever worked for a Trump organization and have ever attended a Trump rally — or anti-Trump organizations or rallies and whether potential jurors are supporters or followers of far-right groups, such as the Proud Boys and Oath Keepers, whose members were among the pro-Trump mob that stormed the U.S. Capitol on Jan. 6, 2021, or of the far-left-leaning collective known as antifa, which resists fascists and neo-Nazis, especially at demonstrations.

WHO’S EXPECTED TO TESTIFY?

Cohen, a Trump loyalist turned critic, is expected to be a key prosecution witness, as he was the one who orchestrated the payoffs. Before testifying in front of the grand jury that brought the indictment last year, Cohen said his goal was “to tell the truth” and insisted he is not seeking revenge but said Trump “needs to be held accountable for his dirty deeds.” Cohen served prison time after pleading guilty in 2018 to federal charges, including campaign finance violations, for arranging the payouts to Daniels and McDougal.

Other expected witnesses include Daniels, whose real name is Stephanie Clifford. Daniels alleges that she had a sexual encounter with Trump in 2006 that she didn’t want, but didn’t say no to. Trump says it never happened.

WHAT WILL TRUMP’S DEFENSE BE?

Trump has denied any wrongdoing and has slammed the case as an effort to hurt his 2024 presidential campaign. Trump has acknowledged reimbursing Cohen for the payment and that it was designed to stop Daniels from going public about the alleged encounter. But Trump said in 2018 it had nothing to do with the campaign.

Trump’s lawyers will likely attack the case by trying to undermine the credibility of prosecution witnesses like Cohen and Daniels. Trump has described the two as liars, testing the limits of a gag order that the judge imposed. It seeks to curtail the president’s inflammatory rhetoric about the case. Trump’s lawyers are expected to paint Cohen as a con man and point to his conviction on multiple federal crimes as well as his disbarment to try to persuade jurors that he can’t be believed.

Trump recently posted on social media a picture of a 2018 written statement from Daniels, in which she denied they had a sexual relationship. Not long after, Daniels recanted the statement and said that a sexual encounter had occurred. She said her denials were due to a non-disclosure agreement and that she signed the statement because the parties involved “made it sound like I had no choice.”

WHAT ABOUT TRUMP’S OTHER CASES?

Trump’s three other criminal cases have gotten bogged down in legal fights and appeals, which may mean jurors won’t hear about them before the November election.

The 2020 election interference case brought by special counsel Jack Smith remains on hold while Trump pursues his claim that he is immune from prosecution for actions he took while in the White House. The U.S. Supreme Court is scheduled to hear arguments on the matter in late April.

The other case brought by Smith accuses Trump of illegally retaining classified documents at his Mar-a-Lago estate. The trial had been scheduled to begin in May, but the judge heard arguments last month to set a new trial date and has yet to do so.

No trial date has been set in the Georgia case accusing Trump and his allies of conspiring to overturn his 2020 election loss in the state. Prosecutors have suggested a trial date of August, but defense attorneys are now urging an appeals court to consider whether Fulton County District Attorney Fani Willis should be disqualified from the prosecution over a romantic relationship she had with a former top prosecutor who recently withdrew from the case.

Trump has pleaded not guilty in all three cases and says he did nothing wrong.