Toronto Mayor Rob Ford has vowed to stay on and run for re-election next year, dismissing calls he resign after admitting he smoked crack cocaine.
Earlier, Mr Ford admitted smoking the drug in a "drunken stupor", though he has said he is neither an addict nor an alcoholic.
He publicly apologised, saying he was "embarrassed" by his behaviour.
"I love my job, I love this city," he said. "I know I have to regain your trust and confidence."
Mr Ford said he had kept his illicit behaviour from his family, staff and political colleagues.
"There is only one person to blame for this and that is myself," he told reporters at a packed press conference on Tuesday.
"Folks, I have nothing left to hide... I would do anything, absolutely anything to change the past, but the past is the past and we must move forward.
"I want to be crystal clear... these mistakes will never, ever, ever happen again."
Mr Ford told reporters earlier in the day he had taken the drug about a year ago. His admission follows revelations that a video apparently showing him smoking crack cocaine - long rumoured in the media to exist but never released publicly - was in the possession of the police.
The mayor had previously called for the release of the video.
"I want everyone in the city to see this tape," he said. "I don't even recall there being a tape or video. I want to see the state that I was in."
Last week, Toronto Police Chief Bill Blair said investigators had recovered footage from a deleted hard drive that appeared to show Mr Ford smoking from a crack pipe.
Police have not revealed details of the mobile phone clip, but say it is consistent with previous descriptions from media organisations that reported viewing it.
The police have also not charged Mr Ford with any offence.
His friend and occasional driver Alexander "Sandro" Lisi faces charges of marijuana trafficking, possession and extortion in connection with the video.
Police have said they expect the video will come out when Mr Lisi goes to trial.
Mr Ford has also challenged allegations he had lied when denying using crack cocaine, telling the media earlier in the day, "I wasn't lying. You didn't ask the correct questions."
Six months ago, the mayor said: "I do not use crack cocaine, nor am I an addict."
The allegations of drug use first surfaced in May after journalists with the gossip website Gawker and the Toronto Star reported seeing the video.
In the intervening months, one city councillor put forward a motion demanding the mayor take a leave of absence and co-operate with a police investigation.
Another councillor, Jaye Robinson, told broadcaster CBC that Mr Ford no longer had "a shred of credibility".