Rep. Katie Hill, D-Calif., on Sunday announced her resignation from Congress amid an ethics inquiry into allegations that she had an intimate relationship with a congressional staff member in her office.

“It is with a broken heart that today I announce my resignation from Congress,” Hill wrote in a statement. “This is the hardest thing I have ever had to do, but I believe it is the best thing for my constituents, my community, and our country.”

Hill’s spokeswoman said that the resignation is not immediate and that Hill is still deciding on when she will leave office. Her announcement was first reported by Politico, which said that she planned to resign by the end of the week.

Last week, the House Ethics Committee opened an investigation of allegations that Hill was involved romantically with her legislative director, Graham Kelly, a relationship that would violate House ethics rules.

Hill also was alleged to have been involved in a three-person relationship with a woman on her campaign team. Hill is openly bisexual.

The allegations first surfaced in a conservative outlet, RedState.org, which published text messages and sexually charged photos.

Hill had accused Republican operatives and her estranged husband of coordinating a “smear campaign” amid the couple’s pending divorce.

In her statement Sunday, she said she is pursuing legal options against those who released private photos, saying that “having private photos of personal moments weaponized against me has been an appalling invasion of my privacy.”

She apologized for “mistakes made along the way and the people who have been hurt.”

Hill, a former nonprofit-group executive from Santa Clarita, California, was considered a rising star in the Democratic Party, unseating longtime incumbent Steve Knight in the 2018 midterm election. Her victory flipped the last Republican congressional seat in Los Angeles County and helped her party regain control of the House.

She was appointed vice chairwoman of the Oversight Committee, and she is among a group of freshman Democrats who earned the nickname “the Big Six” after being selected for high-profile leadership posts.