The former president has asked the Supreme Court to overturn a ruling in Colorado that he is ineligible to appear on the state primary ballot because of his efforts to overturn the 2020 election.

A group of House Democrats on Thursday called on conservative Supreme Court Justice Clarence Thomas to recuse himself from a case involving former President Donald Trump’s eligibility to appear on Colorado’s Republican primary ballot.

Trump on Wednesday asked the Supreme Court to overturn a Colorado court ruling last month that disqualified him from appearing on the ballot over his conduct leading up to the Jan. 6 attack on the Capitol. The former president’s appeal came after the state’s Republican Party filed its own appeal of the Colorado Supreme Court’s decision. The state court put its ruling on hold to allow for appeals, meaning Trump could remain on the ballot pending U.S. Supreme Court action.

A group of House Democrats, led by Rep. Hank Johnson, of Georgia, the ranking member of the House Judiciary Committee’s courts subcommittee, demanded that Thomas recuse himself from the case in a letter dated Thursday.