Washington (CNN) -- Embattled U.S. Rep. David Wu will resign from the House of Representatives after being accused of making unwanted sexual advances toward a fundraiser's daughter, he announced Tuesday.

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.

"I cannot care for my family the way I wish while serving in Congress and fighting these very serious allegations," Wu said. "The well-being of my children must come before anything else."

Gov. John Kitzhaber said he will call for a special election once he has Wu's official resignation.

On Friday, Portland newspaper The Oregonian reported that the daughter of one of Wu's fundraisers 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.

The 56-year-old congressman, who separated from his wife in 2009, disclosed in February that he had sought "professional medical care" after dealing with campaign stress, his responsibilities as a single father and his father's death. The Oregonian reported that campaign aides had confronted him about 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.

Rep. Steve Israel, the chairman of the Democratic Congressional Campaign Committee, said his party has long dominated elections in Oregon's first congressional district, saying that "a Democrat has held this seat in Congress since 1975, Senator John Kerry won this district in 2004 and President Obama won this district with 63 percent in 2008.

"We are confident that a Democrat will continue to represent the families in this overwhelmingly Democratic district."

CNN's Paul Steinhauser contributed to this report.