The appearance for Representative Zach Nunn was another departure from previous norms for the defense secretary, whose predecessors kept a greater distance from politics.
Representative Jimmy Gomez of California acknowledged "personal mistakes" outside his marriage but denied breaking rules that bar relationships with a direct subordinate.
The president also voted by mail in 2020 and in a Florida special election in March, even as he has railed against the practice and equated it to cheating.
The sister of Lindsey Graham was appointed to his Senate seat on an interim basis. She must win a runoff next week against a conservative House member to serve a full six-year term.
The court declined President Trump's long-shot request that it reconsider his appeal. He has separately asked the court to overturn a much larger 2024 award.