The rhetorical battle between President Trump and New York’s attorney general, Letitia James, is escalating, with Mr. Trump railing against her in 12 posts about his ongoing fraud suit in New York over the past day.

Mr. Trump is at New York defending himself and his business from a $250 million suit filed by Ms. James, alleging that he and his business engaged in years of fraud by inflating the value of his assets to secure loans and insurance deals.

Mr. Trump made a rare appearance in court hearings for the case and, based on his Truth Social feed, the suit is a focus of his attention, even as he faces criminal proceedings elsewhere in the country and is running for president.

Ms. James responded to the heated rhetoric coming from Mr. Trump Wednesday evening, indicating that she was unfazed by his comments.

“Today was the third day of our trial against Donald Trump, the Trump organization, and other defendants,” Ms. James said. “Meanwhile, the defendants continued to challenge our case, falsely claiming the underlying law is unconstitutional and other baseless claims, including that this is a witch hunt.”

Some of Mr. Trump’s comments against court staffers and the judge have also resulted in a gag order, a measure that other judges have been reluctant to impose given the former president’s political campaign.

“Dangerous and racist comments will not deter me,” Ms. James said in a statement Wednesday evening. “It is my duty and my responsibility to ensure that the law is enforced and upheld and I refuse to back down or to be bullied.”

Separately, Ms. James has said that Mr. Trump’s comments have “fomented violence” and qualify as “race baiting,” adding, “Mr. Trump is no longer here,” in reference to his voluntary attendance to the hearings, “the Trump show is over.”

Attacking Ms. James has become a major focus of the former president in recent days. He has called the attorney general “Letitia ‘Peekaboo’ James,” “CORRUPT, RACIST, and INCOMPETENT,” and complained that “I don’t even get a Jury” after his attorney failed to request such a trial.

“The ridiculous A.G. case against me in New York, brought by the Racist and Incompetent Peekaboo James, is being studied and mocked all over the World. Companies are Fleeing,” Mr. Trump said early Thursday in a Truth Social post. “I’m in a rat’s nest of NEW YORK DEMOCRAT CORRUPTION.”

Mr. Trump also fired off remarks about the man hearing his case, calling Judge Arthur Engoran a “Radical Left Judge, who came up through Democrat Club System.”

Mr. Trump recently had a gag order placed on him prohibiting the former president from speaking or posting publicly about any member of the judge’s staff. Mr. Trump has previously mentioned a court clerk in his posts, accusing her of being romantically involved with Senator Schumer.

“Schumer’s girlfriend … is running this case against me,” Mr. Trump said. “This case should be dismissed immediately.”

Mr. Trump has also turned the case into an event for his campaign for president, telling reporters Wednesday, “I’d rather be right now in Iowa,” adding, “I’d rather be in New Hampshire or South Carolina or Ohio or a lot of other places.”

In response, Mr. James has said that Mr. Trump’s decision to appear at court was “nothing more than a political stunt” and a “fundraising stop.”