(CNN) — Justice Clarence Thomas and his wife, conservative activist Ginni Thomas, have gone on several luxury trips involving travel subsidized by and stays at properties owned by a GOP megadonor, according to a new bombshell ProPublica report published Thursday.

The hospitality was not disclosed on Thomas' public financial filings with the Supreme Court, ProPublica said.

The report of the connection between Thomas and conservative businessman Harlan Crow is already adding to calls that Congress investigate potential ethical lapses. Key Senate Democrats were previously mulling using this year's funding legislation for the Supreme Court to pressure the justices to adopt some sort of ethics code.

Senate Judiciary Committee Chairman Dick Durbin, an Illinois Democrat, said in a statement the ProPublica report was "a call to action" and that "the Senate Judiciary Committee will act."

The new ProPublica report describes Thomas accepting travel hospitality from Crow that included lavish trips to Indonesia, New Zealand, California, Texas and Georgia. Some of these trips reportedly included travel on Crow's super yacht or stays at properties owned by Crow or his company. ProPublica also identified what appear to be several trips taken by Thomas on Crow's private jet that went undisclosed on his public ethics filings, though one Thomas trip on Crow's jet was disclosed in 1997.

In a statement to ProPublica, Crow said that he been friends with Thomas and his wife Ginni for more than 30 years, and that the hospitality he has extended the justice over the years was "no different from the hospitality we have extended to our many other dear friends."

"Justice Thomas and Ginni never asked for any of this hospitality," Crow said in the statement. He said that we "never asked about a pending or lower court case, and Justice Thomas has never discussed one."

The Supreme Court and Crow did not immediately respond to a CNN request for comment, and ProPublica says Thomas did not respond to a list of detailed questions.

Thomas, nominated by former President George H.W. Bush in 1991, is the senior-most justice on the court and an intellectual leader of the current 6-3 conservative majority. The justice has also been the subject of scrutiny for the political activities of his wife, including for texts she exchanged with key players in former President Donald Trump's attempt to overturn the 2020 presidential election.

Crow, a Dallas businessman with deep connections to Republican politics, has contributed more than $10 million in publicly disclosed political contributions, ProPublica reported.

The ProPublica report documents a painting that hangs at the Crows' Adirondacks property depicting Thomas, Crow and other influential figures in Republican politics, including Leonard Leo, the former Federalist Society head who played a crucial role in Trump's makeover of the federal bench.

Executives of major corporations as well as heads of prominent conservative organizations have been in attendance on trips with Crow that Thomas has joined, the ProPublica report said.

"I am unaware of any of our friends ever lobbying or seeking to influence Justice Thomas on any case, and I would never invite anyone who I believe had any intention of doing that. These are gatherings of friends," Crow's statement to ProPublica said.

Thomas did disclose on his 2001 filings a $19,000 bible that belonged to Frederick Douglass that was gifted to him by the Crow family. ProPublica describes a portrait of the justice and his wife given to him by Crow as well as donation by Crow's foundation of $105,000 for a "Justice Thomas Portrait Fund" at Yale Law School, where Thomas is an alumnus.

Crow, in his statement to ProPublica, acknowledged that he has made "contributions to projects celebrating the life and legacy of Justice Thomas, just as we have done with other great leaders and historically significant figures." He said that neither Thomas nor his wife asked for those contributions.

Calls for tighter disclosure rules for the court

The report comes not long after the federal judiciary's policy-making body quietly adjusted its interpretation of what justices are required to disclose as part of their gifts and hospitality transparency obligations.

Some court ethics experts told ProPublica that the absence of the trips subsidized by Crow — and particularly the travel on his yacht and jet — on Thomas' financial disclosure may have run afoul of the disclosure rules. Under the old guidance, there was some ambiguity about what requires disclosure. For instance, the recent changes clarified that that disclosure was required for personal hospitality subsidized by third parties. That would appear to apply Thomas' stays at the Adirondack property, because it was owned by Crow's company, ProPublica said.

Stephen Gillers, an ethics expert at New York University School of Law, said in an email to CNN Thursday that prior to the recent amendments to the disclosure guidance, Thomas could claim that, because the invitation came from a person — not a corporation or business entity — it did not need to be reported regardless of the value of the gift.

But under the newly-announced changes, Gillers said, "some information and maybe all information about the trips" would have had to be disclosed. The reporting deadline is May 15 of the year following receipt of the gift.

Judges face much looser "hospitality" requirements than members of Congress, who are required to get approval for sponsored trips and who must report within 30 days the other guests and certain financial details about the hospitality, according to Gabe Roth — who leads Fix the Court, a group that advocates for ethics and transparency reforms for the judiciary.

"It's clear that the personal hospitality rules the judiciary adopted last month do not go far enough: the Supreme Court and lower courts need the same, if not stricter, gift and travel rules than what members of Congress have," Roth said in a statement.

Durbin said in his Thursday statement that Thomas' reported behavior was "simply inconsistent with the ethical standards the American people expect of any public servant, let alone a Justice on the Supreme Court."

The updates to the hospitality disclosure guidance was announced in late March by Democratic Sen. Sheldon Whitehouse, who had pressed the Administrative Office of the US Courts for clarification for what falls in the reporting exemption for so-called "personal hospitality."

Whitehouse, who chairs the Judiciary Committee's subcommittee that oversees the judiciary, said on Twitter the new report on Thomas' travel "cries out for the kind of independent investigation that the Supreme Court — and only the Supreme Court, across the entire government — refuses to perform."

"Who were Thomas's companions on these free undisclosed vacations, and what interests did those undisclosed companions have before the Court? The question is obvious," Whitehouse said on Twitter. "All of this needs robust investigation, and it's the Chief Justice's job to make sure that occurs."

This story has been updated with additional developments.

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