The news that the Manhattan district attorney, Alvin Bragg, has invited President Trump to appear before a grand jury in connection with hush money payments to a pornography star, Stormy Daniels, intimates that a remarkable legal U-turn is nearing completion, as such an invitation traditionally is a courtesy that doubles as a prelude to indictment. 

The legal peril for Mr. Trump, reported by the New York Times,  flows from a $130,000 payment made in 2016, while he was running for president, to Ms. Daniels. The funds came from the account of Mr. Trump’s lawyer, Michael Cohen, and were allegedly earmarked for her discretion about a prior sexual encounter.

Prosecutors say that Cohen was then reimbursed for his services, with bonuses to sweeten the deal. He pleaded guilty in 2018 to charges that the payment, and another one like it, violated federal campaign laws. The investigation began under Mr. Bragg’s predecessor, Cyrus Vance Jr.  

Just months ago, it appeared as if Mr. Bragg was quietly quitting this bequest from Mr. Vance, which had expanded to cover Mr. Trump’s business practices and accusations of overvaluing assets. At its prospective zenith, it overlapped with a civil counterpart initiated by New York’s attorney general, Letitia James. 

While Ms. James’s $250 million suit is set to go to trial in October, Mr. Bragg hung back. His reticence precipitated a mutiny, with two senior prosecutors — Carey Dunne and Mark Pomerantz — resigning in protest over his Hamlet-esque approach to charging the former president. The Times reported that he was so doubtful of the case that he stopped presenting grand jury evidence.

Mr. Pomerantz wrote a book detailing his disagreements with Mr. Bragg, “People vs. Donald Trump,” whose publication the district attorney attempted to block because it disclosed confidential deliberations. The disgruntled prosecutor called the investigation the “legal equivalent of a plane crash” and accused Mr. Bragg of “pilot error.” Mr. Trump, he asserted, is guilty of multiple felonies.

The invitation to Mr. Trump to testify next week is unlikely to entice him to take the stand. Empire State law grants immunity for grand jury testimony, a protection that prosecutors will demand Mr. Trump waive if he wishes to tell his side of the story in that forum. Should he do so, that testimony could be used at an ensuing trial.   

If Mr. Bragg decides to hand up charges, it will be the first time a former president will have to mount a criminal defense. While it is not immediately known which charges are being contemplated, they will likely include some combination of falsification of business records and illegal campaign contributions.  

Mr. Trump’s lawyer, Joseph Tacopina, was unmoved by the grand jury invitation, telling the Associated Press that “it’s much ado about nothing.” He added: “It’s just another example of them weaponizing the justice system” against Mr. Trump. He labeled that alleged pattern “sort of unfair.” Mr. Trump also faces the specter of criminal charges in Georgia, Florida, and the District of Columbia.

Mr. Trump took to Truth Social to tar the investigation as a  “political Witch-Hunt trying to take down the leading candidate, by far, in the Republican Party.” A spokesman added that the “Manhattan District Attorney’s threat to indict President Trump is simply insane” and labeled it “an embarrassment.”