Connecticut’s U.S. senators are seeking heightened scrutiny of Justice Clarence Thomas’ undisclosed gifts and deals, raising concerns about the lack of ethical guidelines and transparency surrounding the U.S. Supreme Court.

In the weeks since ProPublica’s report about Thomas accepting luxury gifts and trips from a GOP megadonor, the justice has been under fire as Democratic lawmakers seek his testimony before Congress. Other reports also found undisclosed real estate deals between Thomas and Harlan Crow, including one where Thomas’ mother currently resides.

Sen. Richard Blumenthal, D-Conn., said he believes Thomas, who is serving a lifetime appointment since joining the court in 1991, should resign over his failure to disclose. He wants both Thomas and Crow to testify before the Senate Judiciary Committee in the near future, though the timing and details of any hearings are still fluid. It is unclear if Democrats would ultimately compel them to testify, but Blumenthal said subpoenas should be “on the table.”

“I think he should resign to uphold the Supreme Court and the American justice system. I hope that [Thomas] will voluntarily appear, and if not, we should consider subpoenas for him and others like Harlan Crow who have information,” Blumenthal, a member of the Judiciary Committee, said on Tuesday.

Thomas and Crow, a billionaire real estate developer who has made significant political donations to conservative candidates and causes, have been friends for over two decades.

The justice defended the trips, saying in a statement earlier this month that he was “advised that this sort of personal hospitality from close personal friends, who did not have business before the Court, was not reportable.” But CNN reported Thomas will amend his financial disclosures to include a real estate deal from 2014 with Crow.

“I have endeavored to follow that counsel throughout my tenure, and have always sought to comply with the disclosure guidelines,” Thomas said in an April 7 statement.

As more revelations come to light, Blumenthal said the Judicial Conference — a body created by Congress that considers policy related to the federal courts — and the U.S. Department of Justice should conduct investigations into Thomas’ “dealings with Harlan Crow and others, his failure to disclose, and what other benefits he may have received.”

Recent polling shows Americans’ trust in the high court has significantly waned over the past few years as the high court has been embroiled in controversies related to justice’s families, confirmation hearings and high-profile court decisions. Democrats believe the best way to restore credibility in the Supreme Court is establishing an ethics code for all federal judges.

“The only way we can repair [trust in the Supreme Court] is to get to the truth and assure American people there will be a Department of Justice investigation and that Congress will impose ethical standards through a code, the same that’s applied to any federal judge,” Blumenthal said.

For years, Sen. Chris Murphy, D-Conn., has been one of the biggest advocates for applying such a code to Supreme Court justices. There are general ethics rules, including on recusals and financial disclosures, but there are no formal guidelines for Supreme Court justices.

Murphy has introduced the Supreme Court Ethics Act every session of Congress over the past decade. In his bill, Congress would not be tasked with writing a judicial ethics code and would put the responsibility on the Judicial Conference to create one to govern all federal judges, including the nine justices.

He noted other congressional bills seeking to accomplish a similar goal, including one from Sen. Sheldon Whitehouse, D-R.I., that takes “a more comprehensive approach to Supreme Court ethics.” Blumenthal is a co-sponsor on both Murphy’s and Whitehouse’s legislation.

Any of these bills needs support from at least nine Republican senators if all Democrats are behind it. The bigger challenge would be garnering support from the GOP-led House to take it up and get some Republican lawmakers to vote for it.

Some Republicans have criticized or appeared skeptical of Thomas, while others pointed to The Wall Street Journal editorial board’s characterization of the news as a “smear.” But when it comes to court-related legislation, Murphy noted, there is no political or personal intent behind it.

“The upside of my bill is that it’s clearly not about Clarence Thomas,” Murphy said on Tuesday. “I’ve been introducing this bill for 10 years, so nobody can claim that my piece of legislation is a political hit job on one justice. I’ve thought that the Supreme Court has needed a code of ethics for a decade.”

“I’ve been shopping it to Republicans, although a little more aggressively in the past week,” he added. “No takers yet, unsurprisingly, but I’ll continue to try.”