The New York state judge presiding over Donald J. Trump’s civil fraud trial defended his work on Friday as he rejected a mistrial bid from the former president’s lawyers in which they had accused him of political bias.
The judge, Arthur F. Engoron, a Democrat, has been attacked by Mr. Trump, his lawyer and his allies for his handling of the case, which stems from a lawsuit brought by the New York attorney general.
Mr. Trump called for a mistrial this week, with his lawyers writing that “evidence of apparent and actual bias is tangible and overwhelming.”
Justice Engoron’s denial of the bid doubled as an explanation of his work and that of his law clerk, Allison Greenfield, also a Democrat, who sits on the bench with him at trial and whom he often consults during proceedings.
Mr. Trump and his lawyers have objected to Ms. Greenfield’s prominence and frequent discussions with the judge, arguing that it appears that she is “co-judging.” In calling for a mistrial, they expressed concerns that she, too, was biased.
“My rulings are mine and mine alone,” Justice Engoron wrote in his order on Friday. “There is absolutely no ‘co-judging’ at play. That I may consult on the trial record, the law, and the facts, before issuing any respective ruling is within my absolute discretion.”
A lawyer for Mr. Trump, who is expected to appeal Friday’s decision once the trial has concluded, declined to comment. The proceeding, which began last month and is expected to continue into December, stems from a lawsuit brought against Mr. Trump by the New York attorney general, Letitia James, who is also a Democrat.
The attorney general’s office had asked to respond to Mr. Trump’s arguments, saying that countering them would be helpful to the state’s case should the former president appeal. But Justice Engoron did not give it the chance, calling the arguments for mistrial “utterly without merit” and writing that any response would be “futile.”
Justice Engoron’s order came just a day after an appeals court judge paused gag orders from Justice Engoron that had restricted the former president and his lawyers from attacking court staff, in a seeming rebuke of the trial judge.
Mr. Trump attacked Ms. Greenfield on social media on the first day of the trial, reposting a picture of her with Senator Chuck Schumer, a Democrat, referring to her as “Schumer’s girlfriend” and saying she was “running this case against me.”
Justice Engoron has justified the gag order — and a similar one on Mr. Trump’s lawyers — by saying that the safety of his staff is his top priority and noting that his office had received “hundreds of threatening phone calls, voicemails, emails, letters and packages.”
The appeals court judge, David Friedman, suggested before he paused the gag orders that he also found Ms. Greenfield’s presence on the bench unusual and that he did not think Mr. Trump had said anything that directly threatened her.
Among the issues that Mr. Trump’s lawyers raised in their call for a mistrial were Ms. Greenfield’s donations to Democratic groups, which they cited as among the most troubling evidence of bias.
Justice Engoron addressed that issue directly in his order, writing that Ms. Greenfield had been running for elected judicial office during the time of the donations, which made them allowable under judiciary guidelines.
In any event, he wrote, arguments about Ms. Greenfield’s donations were a “red herring.”
“My principal law clerk does not make rulings or issue orders,” he wrote. “I do.”