In a letter sent to her constituents on Wednesday, Ms. Hill, 32, again denied the allegations and said she was “fully and proactively” cooperating with the Ethics Committee.

But in the letter, she also admitted to a separate relationship with a member of her campaign team.

“I know that even a consensual relationship with a subordinate is inappropriate, but I still allowed it to happen despite my better judgment,” Ms. Hill said in the letter. “For that I apologize. I wish nothing but the best for her and hope everyone respects her privacy in this difficult time.”