• Two leading Democratic senators are pressing Supreme Court Justice Clarence Thomas to reveal whether he repaid a wealthy friend any of the principal for a $267,230 loan he used to buy a luxury motorhome.
• Sens. Ron Wyden and Sheldon Whitehouse raised concerns about potential tax laws Thomas may have violated if the loan was forgiven but not reported on the justice's tax returns.
• The inquiry into the RV loan is only one part of a larger ethics controversy surrounding Thomas.

Two leading Democratic senators are pressing Supreme Court Justice Clarence Thomas to reveal whether he repaid a wealthy friend any of the principal for a $267,230 loan he used to buy a luxury motorhome.

The letter to Thomas' lawyer, dated Tuesday, raises questions about potential tax violations by the conservative justice, who is the longest-serving member of the Supreme Court.

Sens. Ron Wyden, D-Ore., and Sheldon Whitehouse, D-R.I., in their letter, assert that Thomas never repaid a significant portion of the principal loaned to him by his friend Anthony Welters, nor has Thomas said whether the loan was forgiven.

"That such income from the forgiven debt was not reported on any of Justice Thomas's financial disclosure reports raises the possibility that Justice Thomas also did not report such forgiveness as income for tax purposes, as federal law requires," the senators wrote in the letter.

The New York Times first reported in August that Thomas in 1999 paid for his Prevost Le Mirage XL Marathon — a luxury RV — with a loan from Welters, a close friend of his.

The Senate Finance Committee, which Wyden chairs, found in October that Welters "ceased collecting principal or interest on" the loan in late 2008, the new letter noted.

"It appears that no principal was ever repaid on the loan before all payments ceased," the letter said.

Thomas' lawyer, Elliot Berke, told the senators in January that the justice had made payments to Welters "until the terms of the agreement were satisfied in full."

Wyden and Whitehouse called Berke's response a "non-answer" in their Tuesday letter.

"'Satisfied' could have any number of meanings in the context of repayment, forgiveness, or discharge of debt," the senators said in their letter.

"There should be a simple answer as to whether Justice Thomas had hundreds of thousands in debt forgiven so that he could retain possession of a luxury motor coach that doubles as a second home," the senators wrote.

If Thomas' debt to Welters was canceled, forgiven or discharged for less than the amount he owed, Thomas would have had to report the amount as income on his tax returns, the letter noted.

"At the moment, Justice Thomas has done absolutely nothing to address the perception that he may have failed to report hundreds of thousands of dollars in forgiven debt on his federal income tax returns and pay the income taxes owed," the letter said.

"The possibility of a serious tax violation of this kind by a member of the Supreme Court warrants investigation," wrote Wyden and Whitehouse, who chairs the Senate Judiciary Committee's subcommittee on federal courts.

The senators asked Berke to respond with clarification on the terms and repayment of the loan by June 3.

Berke did not immediately respond to CNBC's request for comment.

The inquiry is just one part of a larger ethics controversy surrounding Thomas.

ProPublica reported in April 2023 that the conservative justice for decades accepted luxury vacations from Republican billionaire Harlan Crow — an apparent violation of a financial disclosure law.

Later reports also found that Harlan paid the school tuition of Thomas' great-nephew.

Democrats have also called on Thomas to recuse himself from considering an appeal by former President Donald Trump arguing that he is immune from prosecution in his election interference federal criminal case. Democrats point to reports that his wife, Ginni Thomas, took part in efforts to overturn the results of the 2020 election.

The Supreme Court heard arguments in Trump's immunity appeal on April 25, with Thomas on the bench.