After days of denials, a choked-up Rep. Anthony Weiner confessed Monday that he tweeted a photo of his bulging underpants to a young woman, and he also admitted to "inappropriate" exchanges with six women before and after he got married. He apologized for lying but said he would not resign.

US Congressman Anthony Weiner (D-NY) reacts as he speaks to the press in New York, June 6, 2011. [Photo/Agencies]

"This was me doing a dumb thing and doing it repeatedly and lying about it," the 46-year-old New York Democrat said after a week of double-entendre headlines and late-night wisecracks full of Weiner jokes.

House Democratic leader Nancy Pelosi immediately called for an ethics committee investigation into whether Weiner broke House rules.

The congressman - who was widely expected to run for mayor of New York in 2013 - said at a half-hour news conference that he had never personally met any of the women he corresponded with online and sometimes via telephone over the past three years, and was not even sure of their ages. He also said he had never had sex outside of his marriage.

He said he did not feel the scandal affected his work as a lawmaker but would understand if his constituents decided not to re-elect him. "I'm going to work very hard to win back their trust," he said.

Weiner said he used his home computer and personal Blackberry, not government computers, in his exchanges with the women. But that may not protect him from House rules that say a member "shall conduct himself at all times in a manner that shall reflect creditably on the House."

On numerous occasions, the House ethics committee has cited that general rule in finding a representative violated standard of conduct.

Weiner said over and over that he had made "terrible mistakes" and done "a very dumb thing" for which he alone bore responsibility, and he apologized repeatedly to his wife, Huma Abedin.

"My wife is a remarkable woman. She's not responsible for any of this," he said. "I apologize to her very deeply."

Abedin did not attend his news conference, but Weiner said they would not be separating over the scandal.

The scandal unfolded more than a week ago when a conservative website reported that a photo of a man's crotch had been sent from Weiner's Twitter account to a college student in Seattle.

For days, Weiner claimed that he hadn't sent the photo and that he was the victim of a hacker. But he caused guffaws when he said that he couldn't say with "certitude" that the underwear shot was not a picture of him.

The scandal escalated Monday when the website, BigGovernment.com, run by conservative activist Andrew Breitbart, posted photos purportedly from a second woman who said she received shirtless shots of the congressman. The site said the pictures were in a cache of intimate online photographs, chats and email exchanges the woman claimed to have. The website did not identify the woman.

One photo showed Weiner on a couch with two cats nearby. The website said Weiner sent the photo using the anthonyweiner(at)aol.com account with the subject line "Me and the pussys."

Also, the celebrity website RadarOnline.com said a woman claimed to have 200 sexually explicit messages from Weiner through a Facebook account that Weiner no longer uses. It was not clear whether the woman who claimed to have the new photo was the person who claimed to have received the text messages.

At Monday's news conference, Weiner said he sent the underpants photo as a joke and called it a "hugely regrettable mistake."

"I haven't told the truth and have done things I deeply regret," he said. "I brought pain to people I care about."

ABC News said Monday it planned to air an interview with a Texas woman, Meagan Broussard, who claims to be one of the women who exchanged messages with Weiner. The 26-year-old single mother said she has dozens of emails, Facebook messages and cell phone logs that document more than a month of flirting that started on April 20.

In a strange turn before Weiner's planned news conference, Breitbart took to the podium, defending the accuracy of his posts and saying his reputation was being smeared by the congressman.

The picture showing Weiner shirtless was reminiscent of a photo of former Rep. Chris Lee, a New York Republican who abruptly resigned from office earlier this year after a shirtless photo he sent a woman on Craigslist became public.

Weiner married Abedin, an aide to Hillary Rodham Clinton, last July, with former President Bill Clinton officiating. Before that, Weiner had been known as one of New York's most eligible bachelors.

Weiner began his career as a legislative assistant to then-Rep. Chuck Schumer, now a senator. He was elected to the New York City Council before winning Schumer's House seat in 1998, representing parts of Brooklyn and Queens.

Earlier Monday before Weiner's public admission, New York Mayor Michael Bloomberg was asked whether the congressman could continue to effectively represent New Yorkers.

"It's always up to the constituents," Bloomberg said, adding that it was "time to get back and focus on the serious things."

Weiner gained a national profile during the debate over President Barack Obama's health care plan when he outspokenly professed support for a government-run "single-payer" program for everyone and later a "public option" to compete with private health insurance. He got the notice of liberals even though both proposals failed to make it into law.