Adam Giambrone's short-lived mayoral campaign is officially over.

The announcement was made at a news conference Wednesday morning that saw the 32-year-old councillor abruptly walk off stage after making a brief but emotional statement apologizing for cheating on his live-in girlfriend with several women.

He apologized to his long-term partner Sarah McQuarrie, the public and his colleagues and said that he realized a "public career of integrity cannot survive deceit in my private life."

"There are weeks that change your life, and this one has certainly changed mine," he said, standing at the podium with blood-shot eyes.

But after issuing the apology, he abruptly walked off stage without directly addressing the allegations, discussing his political future or taking questions from reporters.

About two minutes later, his executive assistant came to the podium and indicated he would read out Giambrone's full statement.

"He will spend the next few days in private," said Kevin Beaulieu. "His mayoralty campaign ends today."

Giambrone will stay on as chair of the TTC and will continue his duties as councillor, he said.

Beaulieu did not say whether Giambrone will seek re-election as councillor in his ward.

Toronto Mayor David Miller called Giambrone's decision to step down from the mayoralty race "regrettable."

"His voice and the vision he could have brought to this important campaign will be missed but his decision to focus on his private life and his current duties is understandable," Miller said in a written statement to the media.

Miller, who has long been an ally of Giambrone, did not comment on the councillor's decision to stay on as TTC chair.

Councillor Brian Ashton said the recent problems plaguing the TTC, which have led to a war of words and photographs between TTC employees and customers, should be given priority by the mayor and his beleaguered protégé in the wake of the scandal.

"I would strongly urge Councillor Giambrone to have a serious conversation with the mayor to determine whether or not he feels he has the competence and the confidence of the general public to be able to get a hold of this TTC issue and turn it around," Ashton said.

Several affairs

Giambrone's decision to quit the mayor's race came just hours after a newspaper reported that he had confessed to cheating on his live-in girlfriend several times throughout 2009.

He admitted to having several mistresses after a Toronto university student publicly claimed she started having sex with the 32-year-old TTC chair about a year ago, when she was 19 years old.

Kristen Lucas provided the Toronto Star with several revealing text message exchanges that showed they had a personal relationship.

In one message, Giambrone reportedly says he is in a relationship with McQuarrie because of "political" reasons.

Another message has Giambrone telling Lucas, "I like you because you're smart and interesting. You're also good-looking naked."

The aspiring actress claims she had sex with the politician on his couch at his city hall office. Lucas also told the Star that Giambrone had told her about the TTC fare hike long before the public knew it was coming.

Giambrone has long been considered to be a rising star at city hall, after being elected to office at age 26. A staunch supporter of Miller, Giambrone quickly rose through the ranks to become the chair of the TTC -- one of the most high-profile positions on council.

He announced his bid for mayor early this month at College Street hot-spot Revival, where he was joined by a beaming McQuarrie at the podium.

Councillor Howard Moscoe said that Giambrone would now "have difficulty getting elected as mayor" because of the revelations.

But he added: "What male or female in this city could stand to have their hormones examined publicly?"