Rep. Mark Foley, R-Fla., submitted a letter of resignation from Congress on Friday in the wake of questions about e-mails he wrote a former male page, according to a congressional official.
Foley, 52, had been considered a shoo-in for re-election until the e- mails surfaced in recent days.
Campaign aides had previously acknowledged that the Republican congressman e-mailed the former Capitol page five times, but had said there was nothing inappropriate about the exchange. The page was 16 at the time of the e-mail correspondence.
Foley's election opponent, Democrat Tim Mahoney, has called for an investigation.
The correspondence took place in August 2005 after the boy gave Foley a handwritten thank you note before returning to Louisiana.
Foley was running for re-election to a seventh term. He has represented his district, which includes West Palm Beach, since 1995. Florida Republicans could replace Foley on the ballot.
In his exchanges with the boy, Foley asked how old he was, what he wanted for his upcoming birthday, how he was doing after Hurricane Katrina and for a photo.
The e-mails were posted Friday on Citizens for Responsibility and Ethics in Washington's Web site after ABC News reported their existence. The group asked the House Committee on Standards of Official Conduct to investigate the exchange Foley had with the boy, who served as a page for Rep. Rodney Alexander, R-La.
"The House of Representatives has an obligation to protect the teenagers who come to Congress to learn about the legislative process," the group wrote, adding that the committee, "must investigate any allegation that a page has been subjected to sexual advances by members of the House."