In this Nov. 16, 2016, photo, Federalist Society Executive Vice President Leonard Leo speaks to media at Trump Tower, in New York.
Carolyn Kaster | AP
The Senate Judiciary Committee is expected to vote Thursday to approve subpoenas for two influential conservative political figures: judicial activist Leonard Leo and Harlan Crow, a Republican megadonor whose close friendship with Supreme Court Justice Clarence Thomas has drawn intense scrutiny.
The panel’s Democratic majority says the subpoenas are necessary in response to Leo’s and Crow’s “defensive, dismissive refusals” to fully cooperate with its ethics investigation into the Supreme Court.
The Senate probe stems from a bombshell ProPublica report in April that found Thomas, the most senior justice on the high court, had accepted luxury trips and other gifts from Crow for years without revealing them on his financial disclosures.
Thomas has said he had been advised that he did not have to disclose those items. He and Crow have defended their relationship and maintained that it has not affected Thomas’ business before the court.
Senate Judiciary Chairman Dick Durbin, D-Ill., promptly called for an “enforceable code of conduct” over the Supreme Court, whose nine members face little external oversight.
 “The Senate and the American people deserve to know the full extent of how billionaires and activists with interests before the Court use their immense wealth to buy private access to the justices,” Durbin said Wednesday.
The committee sought testimony from Chief Justice John Roberts, who declined the invitation. In July, the panel in a party-line vote approved legislation to impose binding ethics rules on the justices.
The panel reached out to Crow demanding information, but it said it received an “inadequate” response.
The Democrats later sought information from Leo and two billionaire Republican donors, Paul Singer and Robin Arkley, after they were identified in a separate ProPublica report alleging that Justice Samuel Alito had failed to disclose a luxury Alaskan fishing trip.
Leo and Arkley refused to comply, while Singer provided a limited response, the committee said.
Last month, Durbin announced they would vote to subpoena Crow, Leo and Arkley, accusing the men of “outright defiance of legitimate oversight requests.”
On Wednesday, Durbin announced at the last minute that Arkley would no longer be subpoenaed, saying in a statement that he had “provided the Committee with information that he had been withholding.”
This is developing news. Please check back for updates.
This story originally appeared on CNBC