U.S. Rep. David Wu, D-Ore., will resign following allegations that he had a forced sexual encounter with an 18-year-old woman.

The Oregon Democrat will not step down, however until there is a "resolution" of the debt-ceiling crisis, he said Tuesday.

"The time has come to hand on the privilege of high office," Wu said in a statement. "I cannot care for my family the way I wish while serving in Congress and fighting these very serious allegations."

Wu, first elected in 1998, reportedly told his friend U.S. Rep. John Larson, D-Conn., that he did "nothing illegal" and believes he will be "vindicated."  Maintaining that he would not resign from his post, House Minority Leader Nancy Pelosi, D-Calif., on Monday called for an ethics investigation into the allegations against Wu, who is the first Chinese-American member of Congress.

Initially, the seven-term congressman said he was resolved to finishing out his term, but sid he would not seek re-election next year. Changing course,Wu said his resignation would "avoid any distraction from the important work at hand in Washington."

Seeking counsel from friends, Larson said he told Wu to look to past situations, Fox News reported.

"I said recent evens should guide him as to how things can unravel around here," Larson said, an apparent reference to former U.S. Rep. Anthony Weiner, D-N.Y., who resigned after a sexting scandal. "No one can tell him what to do. And he doesn't have many options."

The Oregonian first reported that a young woman called Wu's Portland office this spring, accusing him of what was described as an "unwanted sexual encounter."  The woman, unnamed by the paper, reportedly left a distraught voicemail accusing Wu of aggressive sexual behavior.

When confronted by his senior staff, Wu admitted to a sexual encounter, but maintained that it was consensual, The Oregonian cited anonymous sources saying. The woman, a daughter of a longtime friend and campaign donor, did not call the police immediately, as she saw it being her word against those of a seven-term congressman.

Wu, 56, separated from his wife in 2009 and has been seeking a divorce.

The news comes after a tumultuous year for Wu, whose political career was threatened in 2010, when staffers accused him of erratic behavior toward the end of his successful re-election campaign. Staffers urged him to check into a psychiatric hospital because of his behavior, but Wu cited stresses of the campaign for his behavior and said he sought treatment for his problems.

In 2004, The Oregonian reported on a 1976 case when Wu was a student at Stanford University and was disciplined for trying to force an ex-girlfriend to have sex.