WASHINGTON — A nearly two-year investigation by Democratic senators of Supreme Court ethics details more luxury travel by Justice Clarence Thomas and urges Congress to establish a way to enforce a new code of conduct.

Any movement on the issue appears unlikely as Republicans prepare to take control of the Senate in January, underscoring the hurdles in imposing restrictions on a separate branch of government even as public confidence in the court has fallen to record lows.

The 93-page report released Saturday by the Democratic majority of the Senate Judiciary Committee found additional travel taken in 2021 by Thomas but not reported on his annual financial disclosure form: a private jet flight to New York’s Adirondacks in July and jet and yacht trip to New York City sponsored by billionaire Harlan Crow in October, one of more than two dozen times detailed in the report that Thomas took luxury travel and gifts from wealthy benefactors.

The court adopted its first code of ethics in 2023, but it leaves compliance to each of the nine justices.

“The highest court in the land can’t have the lowest ethical standards,” the committee chairman, Illinois Sen. Dick Durbin, said in a statement. He has long called for an enforceable code of ethics.

Republicans protested the subpoenas authorized for Crow and others as part of the investigation. No Republicans signed on to the final report, and no formal report from them was expected.

A spokesman for Crow said he voluntarily agreed to provide information for the investigation, which did not pinpoint any specific instances of undue influence. Crow said in a statement that Thomas and his wife Ginni had been unfairly maligned. “They are good and honorable people and no one should be treated this way,” he said.

Attorney Mark Paoletta, a longtime friend of Thomas who has been tapped for the incoming Trump administration, said the report was aimed at conservatives whose rulings Democrats disagreed with.

“This entire investigation was never about ‘ethics’ but about trying to undermine the Supreme Court,” Paoletta said in a statement posted on X.

The court did not immediately respond to a request for comment.

Thomas has said he was not required to disclose the trips that he and his wife took with Crow because the big donor is a close friend of the family and disclosure of that type of travel was not previously required. The new ethics code does explicitly require it, and Thomas has since gone back and reported some travel.

The report traces back to Justice Antonin Scalia, saying he “established the practice” of accepting undisclosed gifts and hundreds of trips over his decades on the bench. The late Justice Ruth Bader Ginsberg and retired Justice Stephen Breyer also took subsided trips but disclosed them on their annual forms, it said.

The investigation found that Thomas has accepted gifts and travel from wealthy benefactors worth more than $4.75 million by some estimates since his 1991 confirmation and failed to disclose much of it. “The number, value, and extravagance of the gifts accepted by Justice Thomas have no comparison in modern American history,” according to the report.

It also detailed a 2008 luxury trip to Alaska taken by Justice Samuel Alito. He has said he was exempted from disclosing the trip under previous ethical rules.

Alito also declined calls to withdraw from cases involving Donald Trump or the Jan. 6, 2021, attack on the Capitol after flags associated with the riot were seen flying at two of Alito’s homes. Alito has said the flags were raised by this wife.

Thomas has ignored calls to step aside from cases involving Trump, too. Ginni Thomas supported Trump’s efforts to overturn the 2020 presidential election that the Republican lost to Democrat Joe Biden.

The report also pointed to scrutiny of Justice Sonia Sotomayor, who, aided by her staff, has advanced sales of her books through college visits over the past decade. Justices have also heard cases involving their book publishers, or involving companies in which justices owned stock.

Biden has been the most prominent Democrat calling for a binding code of conduct. Justice Elena Kaganhas publicly backed adopting an enforcement mechanism, though some ethics experts have said it could be legally tricky.

Justice Neil Gorsuch recently cited the code when he recused himself from an environmental case. He had been facing calls to step aside because the outcome could stand to benefit a Colorado billionaire whom Gorsuch represented before becoming a judge.

The report also calls for changes in the Judicial Conference, the federal courts’ oversight body led by Chief Justice John Roberts, and further investigation by Congress.