Rep. Chris Lee of New York abruptly resigned Wednesday evening, hours after a gossip Web site reported that the married Republican had allegedly sent flirtatious e-mail messages and a shirtless photo of himself to a woman he met online.

Lee experienced his fall from grace in a single afternoon, undone at the speed of the digital age. At lunchtime Wednesday, he was an obscure but promising second-term congressman. Then, at 2:33 p.m., the Web site Gawker posted an alleged e-mail exchange between a man who used Lee's name - but identified himself as a divorced lobbyist - and an unidentified woman. Gawker reported that the two had met through the personals section of Craigslist.

After that, the familiar cycles of a Washington sex scandal were compressed into a blur of tweets and news alerts. There was confusion, a hint of denial, then a pledge from Lee to "work it out" with his wife.

By 6 p.m., a clerk was announcing Lee's resignation in the House chamber.

"I regret the harm that my actions have caused my family, my staff and my constituents," Lee said in a statement. "I deeply and sincerely apologize to them all. I have made profound mistakes and I promise to work as hard as I can to seek their forgiveness."

Lee's statement did not confirm or deny any specific allegations from the Gawker report.

Lee, 46, elected from a district in western New York, was just beginning his second term in Congress. He had been a successful businessman and was known as an up-and-coming Republican voice on financial issues.

This term, he was given a coveted spot on the Ways and Means Committee, which writes tax laws. That was considered a quick rise for a new House member and a sign that he had backers in the GOP establishment.

"Clearly, that doesn't come without somebody loving you somewhere," New York Republican consultant Mike Collins said.

In New York, Lee was known for bringing his wife and young son to campaign events. He had a mostly conservative record during his time in Congress, though on a number of issues he broke with his party; he recently voted with Democrats on an overhaul of the nation's food-safety system and the Children's Health Insurance Program.

Republican consultant Jim Derderian, who worked with Lee on manufacturing and technology issues, said he had a rare talent for deconstructing complex subjects.

"It's a loss to Congress in that respect, because he showed an ability that not many have," Derderian said. "I think it's a shame that that type of perspective - combined with energy - is no longer at our disposal."

The Gawker report cited an account from a woman, whom the site did not name, who said she posted an ad last month on Craigslist's "women seeking men" forum. In the ad, she said she was looking for "financially & emotionally secure" men who don't "look like toads."

That same day, she allegedly received a response from a person who said his name was Christopher Lee, describing himself as a 39-year-old lobbyist, "a very fit fun classy guy. Live in Cap Hill area. 6ft 190lbs blond/blue."

In follow-up e-mails, the man allegedly attached photos - one of himself in a blue polo, the other shirtless. Both of the images bear a significant resemblance to Lee. In its posting, Gawker said the woman cut off the electronic conversation and contacted Gawker after she did an online search for Lee and "concluded he'd lied about his age and occupation."

Gawker said it had confirmed that the e-mail address used to send the messages belonged to Lee.

If the e-mails were sent by Lee, he created a scandal made for the Internet. The allegations were not conveyed in whispers or court affidavits, wrapped up in charges and countercharges. They were conveyed in a photograph of a man making a muscle in a mirror. Lee's problems spread as fast as it took to hit "Forward."

His office first responded, according to Gawker, by saying that the only things Lee had posted online had to do with selling old furniture, and suggesting that Lee's e-mail account had been hacked.

Then, later in the afternoon, a Fox News reporter caught Lee going to his car. "I have to work this out with my wife," he said.

Now, New York Gov. Andrew M. Cuomo (D) must call a special election to fill Lee's seat, which is expected to remain in Republican hands.

On Wednesday, the news moved so quickly that many people back in western New York heard about the resignation before they heard there was a scandal. It left Lee's constituents shocked and scrambling for choices to replace him.

"I think he's blossomed over the last two years," said Richard Yolevich (R), a county legislator in Monroe County. "He was a lot quieter at first. Now, he seems to know - or he seemed to know - what was going on."

"He's an absolute gentleman. I'm shocked. I'm disapppointed," Yolevich said in a phone interview. "My wife's sitting right here. We're both disappointed."

Staff writers Amy Argetsinger and Felicia Sonmez contributed to this report.