NEW YORK Anthony Weiner's improbable campaign for mayor was engulfed Tuesday by a new scandal involving explicit online messages, imperiling his political resurrection two years after he resigned from Congress over similar behavior.
Weiner, appearing solemn and a bit worn as he faced more than 100 journalists at a hastily arranged news conference, acknowledged that his habit of sending sexual images and text messages to female fans had continued for more than a year after he left Congress vowing to seek treatment and change his behavior.
"It's in our rearview mirror, but it's not far," he said.
The revelation collides with the narrative Weiner has offered throughout the campaign, in which he has repeatedly suggested that he has spent his time since leaving Congress rehabilitating himself and repairing his family relationships. After a late entry into the Democratic primary, he had rapidly risen in the polls and performed strongly in fundraising, as his relentless focus on ideas and his omnipresence helped ease the concerns of many voters.
On Tuesday, seeming to recognize the fragility of his public standing, he pleaded with the public to trust his assertions that he is now a changed man, despite the news that his online adventures some conducted under the pseudonym of Carlos Danger had persisted through last summer.
Speaking amid the cramped cubicles of a vacant Chelsea office, Weiner, alternately chastened and defiant, vowed to press ahead with his campaign. His wife, Huma Abedin, stood by his side, at times smiling at him, but at times staring at the floor or at the cabinets behind her.
Publicly airing the couple's private pain, Abedin said her decision to stay with Weiner was "not an easy choice" and said, "Anthony's made some horrible mistakes, both before he resigned from Congress and after."
"We discussed all of this before Anthony decided he would run for mayor, so really what I want to say is, I love him, I have forgiven him, I believe in him," she added.
Abedin, a longtime close aide to Hillary Rodham Clinton, spoke haltingly but candidly about the ups and downs of her marriage, making clear that reconciling with Weiner after the scandal was a long and difficult process.
"It took a lot of work, and a whole lot of therapy, to get to a place where I could forgive Anthony," she said, reading from a prepared text that she slowly unfolded at the podium.
The news startled his aides and prompted three of his rivals in the mayoral campaign Bill de Blasio and Sal Albanese, both Democrats, and John Catsimatidis, a Republican to ask him to drop out.
The New York Times and the National Organization for Women in New York City also called on Weiner to drop out, with the latter calling him "clearly and compellingly unfit for public office."
Weiner was undeterred, saying simply, "I'm sure many of my opponents would like me to drop out of the race."
The turbulent day began when BuzzFeed posted a story calling attention to posts on The Dirty, a website that describes itself as a purveyor of gossip and satire, and warns that its "postings may contain erroneous or inaccurate information."
The Dirty said that it had spoken with a woman, whom it did not name, who provided copies of her communications with a man who was apparently Weiner.
The man engaged in explicit discussions of sexual acts he said he fantasized about performing with her and sent her a picture of his penis; she told him, "Your health care rants were a huge turn-on." The woman, who was 22 at the time, alleged that Weiner offered her an apartment and proposed that he visit her.
But he also seemed aware that the conversations could be dangerous and later asked the woman to "hard delete all our chats." In another exchange, he appeared to be in a reflective mood, and wrote, "I'm deeply flawed."
On Tuesday, Weiner suggested that the essence of the posts was true, although he did not confirm any details.
"While some things that have been posted today are true and some are not, there is no question that what I did was wrong," he said in a statement before the news conference.
Nik Richie, the blogger who posted the exchanges on The Dirty, declined to be interviewed, saying in a statement, "I'm just doing my job."
Even within Weiner's inner circle, which had been shocked by his dishonesty when the scandal first erupted, there was a wave of surprise and dismay over Tuesday's disclosures, according to people close to the campaign. But his advisers said Weiner had not seriously considered withdrawing from the campaign, arguing that he had previously warned the public that there might be new revelations.
"I said that other texts and photos were likely to come out, and today they have," Weiner told reporters. "I want to again say that I am very sorry to anyone who was on the receiving end of these messages and the disruption this has caused."
The timing of the new disclosure, however, is politically perilous.
A New York Times/Siena College poll released last week found that 59 percent of New York City's registered voters said that Weiner deserved another chance at elected office, despite his past behavior. About two-thirds of men said he deserved a second chance, compared with about half of the women.