"During the final tumultuous years of my abusive marriage, I became involved in a relationship with someone on my campaign," Hill said in her letter. "I know that even a consensual relationship with a subordinate is inappropriate, but I still allowed it to happen despite my better judgment. For that I apologize. I wish nothing but the best for her and hope everyone respects her privacy in this difficult time."

The 32-year-old Hill, who identifies as bisexual, again complained about the public release of a nude picture of her allegedly with the female campaign staffer, noting that U.S. Capitol Police are looking into how the photo was released.

Both the nude photo and the initial allegations against Hill were posted by the conservative website RedState.org. The publication reported that Hill had an affair with her legislative director, Graham Kelly. The relationship was purportedly uncovered by Hill's husband, Kenny Heslep. The couple is in the midst of an acrimonious divorce, and there is no proof that an improper relationship with Kelly — who also worked on Hill's campaign — occurred.

Neither Heslep nor Kelly have responded to requests for comment.

"I am saddened that the deeply personal matter of my divorce has been brought into public view, even the false allegations of a relationship with my congressional staffer, which I have publicly denied, and I am fully and proactively cooperating with the Ethics Committee," Hill added in her letter.

Reps. Ted Deutch (D-Fla.) and Kenny Marchant (R-Texas) are the chairman and ranking member of the Ethics Committee. The Ethics Committee — which has subpoena power — initiated the Hill investigation on its own authority, a common practice in high-profile cases.

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Hill is among the most high-profile freshman Democrats — serving as a freshman representative in leadership and as vice chair of the Oversight Committee — and is a sharp critic of President Donald Trump. Hill has told congressional colleagues she has no intention of stepping down from office.

Yet the Hill case may prove a test for Speaker Nancy Pelosi (D-Calif.) and the House Democratic Caucus. Pelosi and other Democrats took a hard line in sexual-harassment cases that emerged out of the #MeToo movement during the last several years, and a number of male lawmakers from both parties were forced to resign under pressure.

This is the first time such allegations have emerged involving a female lawmaker, and Democrats will be under scrutiny as to whether they can apply to same standards to a woman as a man.

Yet the Hill case also involves an alleged incident of "revenge porn," a criminal act in more than 45 states and the District of Columbia. Distribution of the naked photo of Hill shocked and disturbed lawmakers and aides, and there is deep concern among Hill's colleagues that she is the victim of a political smear campaign designed to force her out of office and put her district in play.

