In a statement issued by his office, the seven-term Oregon Democrat said he would step down once the current standoff between Congress and the White House over raising the U.S. debt ceiling is resolved.
On Friday, Portland newspaper The Oregonian reported that the daughter of one of Wu's fund-raisers from Orange County, Calif. accused him of unwanted sexual advances in May. Citing anonymous sources from inside the congressman's office, the Oregonian said the woman, whom it declined to name, left a voice-mail message at Wu's Portland office alleging aggressive advances.
According to the newspaper, the woman was 18 when the alleged incident took place in November and it was never reported to police.
With House Democratic leader Nancy Pelosi seeking an ethics investigation after Friday's news and calls for his resignation mounting back home, the congressman's spokesman said Monday that he would not seek re-election and was "considering all options" regarding the rest of his term.
In February, the 56-year-old congressman disclosed that he had sought "professional medical care" after the Oregonian reported that campaign aides had confronted him over his erratic behavior and use of medication during his 2010 re-election bid.
"I fully acknowledge that I could have dealt with these difficult circumstances better, and I remain focused on being a good father to my children and a strong representative for the people of Oregon," he said at the time.
Wu's Portland-area district is heavily Democratic, and he won each of his races by double-digit margins.