A federal judge on Thursday rejected President Trump’s latest effort to block the Manhattan district attorney from obtaining his tax returns, roundly dismissing Mr. Trump’s arguments that the prosecutor’s grand jury subpoena was “wildly overbroad” and issued in bad faith.

The ruling by Judge Victor Marrero of Federal District Court in Manhattan marked another setback for the president in his yearlong legal fight to block the subpoena. The conflict has already reached the Supreme Court once and could end up there again if, as expected, Mr. Trump appeals.

The district attorney, Cyrus R. Vance Jr., a Democrat, has been seeking eight years of Mr. Trump’s personal and business returns and other financial records as part of an investigation into the president’s business practices.

Judge Marrero dismissed the president’s argument that Mr. Vance had embarked on a politically motivated fishing expedition, saying in his decision that “established judicial process” did not “automatically transform into an incidence of incapacitating harassment and ill-will merely because the proceedings potentially may implicate the president.”

Judge Marrero was appointed to the federal bench in 1999 by President Bill Clinton.

The Supreme Court, in a landmark decision in July, rejected Mr. Trump’s initial argument that a sitting president had immunity from criminal investigation. But that ruling opened the door for the president to return to the lower court in Manhattan and raise other objections to the subpoena.

Mr. Trump renewed his fight in July with a new argument that the subpoena was overbroad, seeking information far beyond the jurisdiction of a local district attorney.

But in his decision on Thursday, Judge Marrero agreed with Mr. Vance’s argument that throwing out the subpoena would effectively amount to shielding the president and his associates from an investigation, potentially allowing the statute of limitations to expire on any potential crimes.

“At its core, it amounts to absolute immunity through a back door,” Judge Marrero wrote.

A spokesman for Mr. Vance declined to comment. A lawyer for Mr. Trump did not immediately respond to requests for comment.

It has been known that Mr. Vance was investigating whether any New York State laws were broken when hush-money payments were made in the run-up to the 2016 president election to two women who said that they had affairs with Mr. Trump.

But Mr. Vance’s office suggested recently in a court filing that its inquiry was broader, also focusing on potential bank and insurance fraud.

The prosecutors, defending their subpoena for Mr. Trump’s records, cited undisputed “public reports of possibly extensive and protracted criminal conduct at the Trump Organization.” Mr. Vance’s office made it clear in court recently that it viewed the tax returns as central evidence in its investigation.

The New York Times also has reported that Mr. Vance’s office issued a separate subpoena to the president’s longtime lender, Deutsche Bank, seeking records that Mr. Trump and his company provided to the bank when he sought loans. The bank complied with the request, The Times reported, although there was no indication the bank’s records included Mr. Trump’s tax returns.

Mr. Vance’s subpoena for Mr. Trump’s tax returns was sent in August 2019 to the president’s accounting firm, Mazars USA.

Mr. Trump quickly filed suit in Federal District Court in Manhattan, where he made his initial argument about immunity.

Judge Marrero, in a 75-page decision last October, rejected that position, calling the argument that Mr. Trump was immune from criminal investigation “repugnant to the nation’s governmental structure and constitutional values.”

In that ruling, Judge Marrero also said that “barring a stronger showing from the president,” he did not believe the district attorney was acting in bad faith.

Eventually, the case reached the Supreme Court, which last month ruled against Mr. Trump by a vote of 7 to 2. “No citizen, not even the president, is categorically above the common duty to produce evidence when called upon in a criminal proceeding,” Chief Justice John G. Roberts Jr. wrote for the majority.

Chief Justice Roberts said, however, that Mr. Trump still could raise objections to the scope and relevance of the subpoena, which resulted in the president’s new arguments before Judge Marrero.

“The Mazars subpoena is so sweeping,” Mr. Trump’s lawyers last month told Judge Marrero in court papers, “that it amounts to an unguided and unlawful fishing expedition into the president’s personal financial and business dealings.”

Even if Mr. Vance were to obtain the tax records, they would be covered by grand jury secrecy rules and would most likely not become public. They might surface in public only if charges were later filed and they were introduced as evidence in a trial.