The race for the next mayor of Canada’s most populous city officially got underway Monday, with top Liberal organizer Rocco Rossi first out of the gate and former deputy premier George Smitherman removing the last barrier to a long-anticipated run at the top job.

Smitherman, who resigned from cabinet in November, gave up the provincial seat he’s held for more than a decade on Sunday to pave the way for his bid to become Toronto’s next mayor.

Known as Premier Dalton McGuinty’s right-hand man and top enforcer, the lifelong Liberal said vacating his downtown riding of Toronto Centre was a difficult but necessary step.

“It was very tough,” he said in an interview.

Smitherman, who’s currently on vacation with his husband, was tight-lipped about when he’ll register as a candidate, but said he’s ready to tackle the rigours of an election campaign.

“Different candidates have different timelines, but I will do that quite soon,” he said.

Monday marked the first day that candidates could file nomination papers for the Oct. 25 election, and Rossi wasted no time in putting his name on the ballot.

The former national director of the federal Liberal party reiterated his pledge to cut his salary by 10 per cent if elected and sell Toronto Hydro to tackle the city’s $2.5-billion debt.

“It’s a fabulous asset, but it’s not essential to running a city, whereas having proper transit is something that’s central to the function,” he told CP24. “And quite frankly, we’re at the limits of what we can borrow already.”

Rossi will likely be pitted against Smitherman and his old foe John Tory, the ex-leader of the Ontario Progressive Conservatives who now hosts a talk radio show in Toronto.

Tory, a wealthy and well-connected backroom operative for former prime ministers Brian Mulroney and Kim Campbell, is mulling another shot at the city’s top job after losing to David Miller in 2003.

He confirmed that he wouldn’t file any papers Monday, but one insider said Tory will likely announce his intentions over the next few weeks.

“John hasn’t officially declared yet,” the source said. “I fully expect him to be a candidate and he will likely register certainly before the end of the month.”

Insiders say the Toronto mayoral hopefuls will likely need to raise between $1.5 million to $2 million to run an effective campaign, but they can’t collect donations or spend money until they’ve officially registered as candidates.

That won’t be the only obstacle they face. Tory and Smitherman are both carrying plenty of political baggage that could haunt them in the mayoral race, said one expert.

The former health minister could be hurt by Ontario’s eHealth spending scandal as well as his reputation as McGuinty’s attack dog in the legislature, said David Docherty, a politics professor at Wilfrid Laurier University.

Smitherman is quick and bright, but may have to temper his aggressive political style to show voters that he can work with all 44 councillors and play the city hall coalitions to get things done, he said. Tory, meanwhile, will likely have to overcome the stigma of losing elections at both the municipal and provincial level.

“I’m sure I’m not the first person to say that he will probably be labelled as a two-time loser,” Docherty said.

But many of the things that made Tory a bad party leader _ such as his tendency to talk about both sides of an issue, rather than opposing the government at every opportunity _ could actually make him a better mayor, he said.

“The magic number is the number of votes it takes to get things passed and your ability to work with people and listen to reasoned arguments on both sides,” Docherty said.

“That actually is one of Mr. Tory’s strengths. His opponents will say he’s wishy-washy, he’ll say he’s consultative.”

Toronto also has a long history of embracing so-called Red Tories like him as their mayor, including David Crombie, he added.

Coun. Giorgio Mammoliti said he’ll file later this week. He may be joined by another city councillor, Adam Giambrone, who has also mused about throwing his hat into the ring. Candidates have until Sept. 10 to file the necessary paperwork.

McGuinty has indicated that he’ll move quickly to call a byelection in the riding of Toronto Centre, which Smitherman has represented since 1999.

Ex-Winnipeg mayor Glen Murray – once considered a potential rival to Smitherman in the mayoral race – is expected to win the Liberal nomination to replace Smitherman at a meeting Wednesday, backed by key party members.

McGuinty is also expected to shuffle his cabinet to find a permanent replacement for Smitherman, whose massive energy and infrastructure portfolio was temporarily assumed by veteran Liberal Gerry Phillips.

There may be more cabinet exits to come, such as Municipal Affairs and Housing Minister Jim Watson, who is rumoured to be considering a run for Ottawa mayor.