WASHINGTON - New York Rep. Anthony Weiner denied Wednesday he sent a lewd photo from his Twitter account to a 21-year-old woman, trying to calm a media furor that has only increased by the day and wasn't put to rest by the combative lawmaker's latest comments.

Weiner, a Democrat, acknowledged to an MSNBC reporter that he "can't say with certitude" that the photo of a man's bulging underpants wasn't him, but when asked how he could fail to remember having such a picture, he did not directly respond.

The congressman told MSNBC on Wednesday that he did not send the photo and that it was the work of a hacker. He also said he had retained an attorney and hired a private security company to figure out how someone could pull off such a prank.

The photo was posted Friday and sent to a female college student in Seattle. It was quickly deleted, but a frenzy of comment ensued in blogs and cable news outlets.

The congressman, who represents parts of Brooklyn and Queens, was characteristically sharp-tongued Tuesday, refusing to answer reporters' questions and even calling one a "jackass" for interrupting him.

But that changed Wednesday, as it became clear that the story wasn't fading.

Weiner failed in a 2005 bid for the Democratic nomination for mayor of New York City, but he is widely considered a future contender for the office.

The tweet of the photo first was reported Saturday by BigGovernment.com, a website run by the conservative commentator Andrew Breitbart.

The woman told the New York Daily News that she had never met Weiner and that there had "never been any inappropriate exchanges" between her and him. Weiner, 46, is married to Huma Abedin, an aide to Secretary of State Hillary Rodham Clinton.