President Trump is expected to be back in a New York court today for a hearing that could decide whether the former president’s first criminal trial begins in just 39 days.

The hearing to determine whether Mr. Trump’s March 25 hush-money trial date holds will be held in the same Manhattan courtroom where he pleaded not guilty last April to 34 counts of falsifying business records in an alleged scheme to bury stories about extramarital affairs that arose during his 2016 presidential campaign.

It would be Mr. Trump’s first return visit to court in the New York criminal case since that historic indictment made him the first ex-president charged with a crime. Since then, he has also been indicted in Florida, Georgia, and Washington, D.C.

Judge Juan Manuel Merchan has taken steps in recent weeks to prepare for a trial. If it goes off as planned, it would be the first of Mr. Trump’s four criminal cases to go to trial.

Over the past year, Mr. Trump has lashed out at Judge Merchan as a “Trump-hating judge,” asked him to step down from the case and sought to move the case from state court to federal court, all to no avail. 

Judge Merchan has acknowledged making several small donations to Democrats, including $15 to Mr. Trump’s rival, President Biden, but said he’s certain of his “ability to be fair and impartial.”

Thursday’s proceeding is part of a busy, overlapping stretch of legal activity for the Republican presidential front-runner, who has increasingly made his court involvement part of his political campaign.

The recent postponement of a March 4 trial date in Mr. Trump’s Washington, D.C. election interference case removed a major hurdle to starting the New York case on time.

Just as the New York hearing is getting underway, a judge at Atlanta is set to hear arguments Thursday over whether the Fulton County district attorney, Fani Willis, should be disqualified from Mr. Trump’s Georgia election interference case because of a “personal relationship” with a special prosecutor she hired for the case, Nathan Wade.

Mr. Trump is also awaiting a decision, possibly as early as Friday, in a New York civil fraud case that threatens to upend his real estate empire. 

If the judge rules against Mr. Trump, who is accused of inflating his wealth to defraud banks, insurers and others, he could be on the hook for millions of dollars in penalties among other sanctions.

Along with clarifying the trial schedule, Judge Merchan is also expected to rule on key pretrial issues, including a request by Mr. Trump’s lawyers to throw out the case, which they have decried in court papers as a “discombobulated package of politically motivated charges marred by legal defects.”

Mr. Trump’s lawyers, Todd Blanche and Susan Necheles, accuse the Manhattan district attorney, Alvin Bragg, a Democrat, of bringing the case to interfere with Mr. Trump’s chances of retaking the White House. Mr. Bragg’s predecessor, Cyrus Vance Jr., declined to pursue a case on the same allegations.

The charges are punishable by up to four years in prison, though there is no guarantee that a conviction would result in prison time.

The case centers on payoffs to two women, adult film actress Stormy Daniels and former Playboy model Karen McDougal, as well as to a Trump Tower doorman who claimed to have a story about Mr. Trump having a child out of wedlock. Mr. Trump says he didn’t have any of the alleged sexual encounters.

Mr. Trump’s lawyer at the time, Michael Cohen, paid Ms. Daniels $130,000 and arranged for the publisher of the National Enquirer supermarket tabloid to pay Ms. McDougal $150,000 in a practice known as “catch-and-kill.”

Trump’s company then paid Mr. Cohen $420,000 and logged the payments as legal expenses, not reimbursements, prosecutors said. Mr. Bragg charged Mr. Trump last year with falsifying internal records kept by his company, the Trump Organization, to hide the true nature of payments.

Mr. Trump’s legal team has argued that no crime was committed.