(CNN) -- Rep. Anthony Weiner, a New York Democrat, has been under fire ever since a lewd photo appeared on his Twitter account last month. Considered one of the leading liberal voices in the House, the seven-term congressman is now battling for his political life.
Here are key dates in the snowballing scandal:
-- May 27, 2011: A lewd photo appears briefly on Weiner's Twitter account. Conservative blogger Andrew Breitbart is first to report the image, which shows the bulging crotch of a man in his underwear. The story goes viral.
-- May 30, 2011: The congressman tells reporters a hacker got control of his social networking account. "Look, this is a prank and not a terribly creative one," Weiner says. A spokesman says the congressman has retained an attorney to look into the situation, but Capitol Police and the FBI tell CNN they are not investigating.
-- May 31, 2011: Weiner repeatedly dodges reporters' questions about the Twitter post, saying the matter is a distraction and undeserving of further attention. "I'm going to get back to the conversation I care about," he says. Weiner declines to answer whether he is the man in the photo.
-- June 1, 2011: Weiner tells CNN's Wolf Blitzer that he did not post the picture and says he has hired a law firm to investigate. He continues to evade the question as to whether the now-notorious photo is of him.
-- June 3, 2011: Weiner cancels a speech he was scheduled to make at the Wisconsin Democratic Party convention. Privately, members of the House Democratic leadership begin to push Weiner to end what many now see as an unwelcome diversion.
-- June 6, 2011: In an abrupt about-face, a tearful Weiner apologizes for falsely claiming that his Twitter account was hacked and admits to having engaged in inappropriate relationships with several women he met online. He tells reporters he will not resign, nor does he plan to separate from his wife. "To be clear, the picture was of me, and I sent it," Weiner says.
-- House Democratic Leader Nancy Pelosi calls for an ethics committee investigation to determine if government resources were used or House rules violated in Weiner's online relationships. The congressman claims he does not believe he used any government resources, but says he would "welcome and fully cooperate" with a probe.
Earlier in the day, conservative blogger Breitbart published new images that purportedly showed Weiner shirtless.
-- June 7, 2011: Democratic leaders begin to turn on Weiner. "I wish there was some way I could defend him, but I can't," says Senate Majority Leader Harry Reid, D-Nevada. Two House Democrats say they will donate campaign contributions from the embattled congressman to charity.
-- June 8, 2011: Tim Kaine, the former chairman of the Democratic National Committee, calls on Weiner to resign, becoming the first prominent Democrat to publicly demand his resignation. A photo that blogger Breitbart claims shows the naked genitals of Weiner finds its way to the Internet.
-- June 9, 2011: Sen. Patrick Leahy adds his voice to calls for Weiner to resign from his seat in the House. Weiner says he has no plans to step down and that his wife wants him to stay in Congress, according to a Democratic source. A Marist College poll shows that a majority of registered voters in Weiner's district -- 56% -- don't believe he should resign.
CNN learns that Weiner and his wife, Huma Abedin, are expecting their first child.
-- June 11, 2011: The head of the Democratic National Committee calls for Weiner's resignation, as does House Democratic leader Pelosi and Democratic Congressional Campaign Committee chair Steve Israel.
Weiner decides to seek treatment "to focus on becoming a better husband and healthier person" and will ask for a "short leave of absence" from Congress, his spokeswoman says. It was not clear what type of treatment he would undergo.
-- June 12, 2011: TMZ publishes photos of Weiner, in various states of undress, which he apparently took of himself in a locker room. TMZ reports that they were taken in the House members' gym and sent to at least one woman. Weiner's office had no immediate comment, and CNN could not confirm the details as reported by TMZ.
The heads of both major political parties battle over the handling of Weiner's scandal, with the Republican Party boss accusing Democrats of inaction and the Democratic Party leader accusing Republicans of a "double standard."