Associate Supreme Court Justice Clarence Thomas arrives for the swearing in ceremony of Judge Neil Gorsuch as an Associate Supreme Court Justice in the Rose Garden of the White House in Washington
Associate Supreme Court Justice Clarence Thomas arrives for the swearing in ceremony of Judge Neil Gorsuch as an Associate Supreme Court Justice in the Rose Garden of the White House in Washington, U.S., April 10, 2017. Reuters

Senate Judiciary Committee Democrats on Monday urged U.S. Chief Justice John Roberts to investigate luxury trips taken by Supreme Court Justice Clarence Thomas that were paid for by a Republican donor - conduct they deemed inconsistent with ethical standards for "any person in a position of public trust."

The committee will hold a hearing in the coming days on the matter, Chairman Richard Durbin and the panel's 10 other Democratic members wrote in a letter to Roberts. The hearing, they said, would focus on "the need to restore confidence in the Supreme Court's ethical standards."

"And if the court does not resolve this issue on its own, the committee will consider legislation to resolve it," they told Roberts. "But you do not need to wait for Congress to act to undertake your own investigation into the reported conduct and to ensure that it cannot happen again. We urge you to do so."

ProPublica reported on Thursday that Thomas accepted expensive trips from Republican donor and real estate magnate Harlan Crow over decades without disclosing them.

Thomas defended the trips on Friday, saying he had been advised he was not required to report that type of "personal hospitality." But the conservative justice said he would abide by new, tighter rules that recently took effect.

Crow told ProPublica he had "never sought to influence Justice Thomas on any legal or political issue."

The senators in the letter told Roberts that "you have a role to play as well, both in investigating how such conduct could take place at the court under your watch, and in ensuring that such conduct does not happen again."

The report by ProPublica found that Thomas had repeatedly vacationed with Crow, including on his private jet and superyacht in the United States and around the globe. The news outlet said the frequency of the gifts have "no known precedent in the modern history of the U.S. Supreme Court."

"The report describes conduct by a sitting justice that he did not disclose to the public and that is plainly inconsistent with the ethical standards the American people expect of any person in a position of public trust," the senators wrote.