Rep. Anthony Weiner, a rising star in Democratic politics who has long aspired to be mayor of New York City, admitted Monday to having inappropriate online exchanges with at least six women and repeatedly lying about his role in sending a sexually suggestive photograph to a young woman over Twitter last month.

After a week of sometimes indignant public denials and insistence that he was the victim of an Internet hacker, a weeping and stammering Weiner, 46, acknowledged at a news conference that he had sent the photo of himself in his underwear to the woman in Seattle.

The six-term congressman from Brooklyn insisted that he had broken no laws and vowed to remain in office, calling the matter an "aberration from which I've learned."

During an extraordinary 27-minute appearance, the congressman went on to describe a side of his life that he had kept secret from his closest confidants and family members, in which he befriended young female admirers over the Internet and engaged in intimate sexual banter with them.

"Over the past few years, I have engaged in several inappropriate conversations conducted over Twitter, Facebook, email and occasionally on the phone with women I had met online," Weiner said.

'A destructive thing'

Weiner said he had never met in person the women with whom he corresponded and added: "I don't know what I was thinking. This was a destructive thing to do. I'm apologetic for doing it."

But Weiner's political standing appeared in grave danger after his news conference. There was a striking absence of any public expressions of support from his colleagues, and the House Democratic leader, Rep. Nancy Pelosi, called for an ethics investigation into Weiner's conduct.

"I am deeply disappointed and saddened about this situation," she said.

House ethics rules state that members should conduct themselves "at all times in a manner that shall reflect creditably on the House."

Weiner's public confession was prompted Monday when Andrew Breitbart, a conservative blogger and provocative critic of the left, followed through on a vow to publish photographs of Weiner that the congressman had sent to a woman online.

As Breitbart began to unveil the photos one by one, from midmorning until early afternoon, Weiner's staff seemed paralyzed, failing to answer questions or challenge the authenticity of the photographs.

One of the pictures showed Weiner, his wedding ring visible, holding up a sign identifying himself to the woman, who had expressed skepticism that she was exchanging messages with the congressman. The most explicit featured Weiner, bare-chested at his home computer, with a row of family photos arranged behind him.

Weiner had gained renown for his devoted and deft use of social media like Twitter and Facebook, cultivating thousands of admiring followers with a near-constant stream of political riffs and punchy one-liners.

In the end, however, it was his reckless approach to those online tools that led to his undoing.

At the news conference, he said that the online relationships with the women had begun three years ago and that several of them began after he was married in July to Huma Abedin, a longtime aide to Secretary of State Hillary Rodham Clinton, in a grand service officiated by President Bill Clinton.

While he repeatedly emphasized his failings, Weiner stressed that he had not had physical contact with any of the six women and said he believed they were all adults.

"At least to the extent of my knowledge," he said, when pressed about their ages and the tendency toward exaggeration on the Web. At another point, Weiner declared: "I've never had sex outside of my marriage."

He repeatedly apologized to his wife, who, unlike other spouses of misbehaving male politicians, did not appear at his side: "I love my wife very much, and we have no intention of splitting up over this. We have been through a great deal together, and we will -- we will weather this. I love her very much, and she loves me."

Mayoral ambitions

The news conference was a singular, at times surreal, spectacle: the House's most pugilistic and defiant liberal -- famed for skewering his rivals in YouTube-ready bursts of indignation -- suddenly appearing, on live TV, as penitent, teary figure behind a spare wooden podium.

The episode, with its traces of digital deception, echoed the swift political fall of Weiner's fellow House member, Christopher Lee, a New York Republican who emailed a shirtless photo of himself to a woman he met online. Lee resigned.

Even if Weiner remains in office, however, political consultants said his ultimate ambition, to succeed Michael Bloomberg as mayor, has very likely been extinguished.

"There is zero chance today of a Mayor Weiner," said Hank Sheinkopf, a veteran political analyst who has worked on New York City mayoral campaigns for decades. "Mayors don't do these things. It's too much already."

Weiner's ordeal began two Fridays ago, on May 27, at 11:35 p.m.: A Twitter post, containing the photo of gray boxers, was sent from Weiner's account to that of a college student in Washington state, assuming it would remain private.

He called it "part of a joke" to the woman.

But he soon panicked, went online and tried to delete the photo. It was too late: The image had not been private, after all. It was immediately copied and redistributed across the Internet.

Now powerless to erase an embarrassing image of his own groin from the all-seeing eyes of the Web, Weiner told his staff that his account had been hacked.

On May 29, a spokesman told the news media that "Anthony's accounts were obviously hacked" and that the congressman had asked a lawyer to advise on how to proceed.

But he declined to answer basic questions about the origins of the photo, first in a testy exchange with reporters on Capitol Hill, and then in a series of increasingly fraught interviews with major news outlets.

At one point, Weiner admitted that he could not say with "certitude" whether or not the man in the photo was him.