After months of speculation about his future in politics, Gérald Tremblay has stepped down from his position as mayor of Montreal.

"I am leaving public life," said Tremblay on Monday evening at a hastily organized news conference at Montreal's city hall.

He continued to deny any direct knowledge of corruption within his administration, and he said "crooks" within his circle had betrayed his trust. But facing allegations that he had turned a blind eye to corruption and electoral misspending by his Union Montréal party, Tremblay said he had no choice but to resign.

"I cannot help in these circumstances," said Tremblay. "The city's functioning is much more important than my own personal interest."

Tremblay stands by his legacy

"When I was a young man, my father told me never to get into politics," said Tremblay, "because it was dirty and would destroy me."

"Gérald Tremblay was not a person, it was a regime." —Richard Bergeron, Projet Montréal leader

Tremblay, 70, said that when he decided to run for the mayor's position, he knew he was "inheriting a city technically bankrupt with a democratic deficit, with chronic under-investment in infrastructure, not much passion for the most needy of our society, no transportation plan, a moratorium in the development of green spaces, no cultural policy and no shared vision for the Montreal metropolitan community."

Tremblay said he believed he had made changes for the better, leaving the city with a better financial picture, a public consultation process for citizens, the office of the ombudsman and the Montreal Charter of Rights and Responsibilities.

'Brown envelopes' were only rumours, Tremblay says

Looking back at the start of his mandate as mayor in 2001, he said that during his first meeting with the city's director-general, he was told that brown envelopes of cash were circulating within certain municipal departments.

Tremblay said he asked the director-general what he had done about it, only to be told no one had come forward with evidence.

He insisted he had been vigilant, but said it was only after the fact that he had been provided with documents detailing two of the worst scandals faced by his administration: the Faubourg-Contrecoeur land deal, which saw public property sold to developer Frank Catania for a pittance, and the water-meter scandal, involving the largest contract ever awarded in the city's history.

"I asked the public servants and the councillors why I had not been informed about this, especially when individuals in charge had done nothing," said Tremblay. "The trust I had in some was inevitably betrayed. I assume full responsibility."

The outgoing mayor then said he took appropriate steps every time he heard of collusion or corruption within his administration.

"The information was immediately given to the appropriate authorities. I shall produce the proof at the right time and at the right place," said Tremblay.

He said he sought a third mandate in 2009, despite what he called "the storm" that raged around him with allegations of corruption, because he felt he was the best person to "clean up."

"I fervently hope that one day there will be recognition.… that I fought, often alone, this system of collusion and corruption," Tremblay said, "as the Charbonneau commission is revealing, it has existed since at least 1988."

Tremblay blamed the former provincial government for not acting urgently enough on corruption allegations.

He said he had provided the Charbonneau inquiry with "the truth," but has not been invited to appear as a witness in the near future.

"I am not part of the commission's game plan — at least not in the short term," he said.

He used the platform of his farewell speech to deny vehemently allegations made at the inquiry — that he'd been aware of double-bookkeeping within his party.

He also denied knowing about the existence of an "unofficial" budget, something former party organizer Martin Dumont alleged at the province's corruption inquiry.

Tremblay ended his speech by thanking his party, his wife and family and by saying he was a victim of "an unbearable injustice."

"But one day, justice will prevail," he said.

'The Tremblay era is done'

By law, the city council will have to hold a secret ballot vote to elect an interim mayor because Tremblay is leaving his position less than a year before the preset election date.

After Tremblay's announcement,  the leader of Projet Montréal, Richard Bergeron, told reporters that the mayor's departure will give city council the opportunity to "take Montreal out of this crisis."

The decision on an interim mayor will be a big one to make, since the chosen representative will have to guide the city through "one of the worst crises Montreal has ever seen," according to Bergeron.

"Gérald Tremblay was not a person, it was a regime," added Bergeron. "This regime is looking to perpetually repeat itself. I have trust in Montreal's elected officials that, in the coming days ... I hope that everyone will be responsible during this delicate exercise."

"The Tremblay era is done," said Bergeron.

He did 'the only thing that was left to do'

Louise Harel, leader of Vision Montréal, said Tremblay's decision was inevitable considering the allegations he has been facing.

"He did the only thing that was left to do," said Harel. "He lost the trust of the Montrealers and he had to resign."

Harel added that the former mayor put faith in the wrong people.

"Gérald Tremblay says, 'My trust was betrayed,' but it shows that he certainly is trusting too much his entourage," said Harel. "You know, he didn't want to know. I think that it's impossible not knowing what happens in his own administration, because he has a responsibility to take care of this administration, to take care of the city."

The opposition leader said most of city council's work will now have to focus on regaining the population's trust.

Harel added that Tremblay played victim. "For [Tremblay], he is a victim. A victim of all the people, his entourage, his colleagues, Quebec … all governments, so on. And, it's sure that one day he will have to [review his conscience]."