This week, the would-be leaders of the Conservative Party of Canada entered the home stretch, and it’s starting to look like it will be pretty tough for anyone to catch up to the three frontrunners.

At the head of of the pack we have Kevin O’Leary, Maxime Bernier and Kellie Leitch — the only three who look to have a real shot at crossing the finish line first.

Behind them, half a lap back, are Lisa Raitt, Erin O’Toole, Andrew Scheer, Chris Alexander, Brad Trost and Michael Chong. It’s hard to imagine any of them catching the frontrunners now, but there are months to go before Conservatives vote, and the frontrunners are all capable of messing up in some way that would change the dynamic.

O’Leary is ahead of Bernier and Leitch, but his support can’t be as solid as his rivals’. Bernier was first elected in 2006 and served Stephen Harper as minister of foreign affairs, minister of industry and secretary of state for small business, tourism and agriculture. Leitch was first elected in 2011 and served as Harper’s minister of labour and status of women.

Forget, if you can, that Bernier lost his job as foreign affairs minister after he left secret documents in the apartment of a woman linked to the Hells Angels, and forget that in the last election campaign Leitch was the pitchwoman for a proposed snitch line to report “barbaric cultural practices.”

At least we know them, in part because they are both longtime residents of Canada — unlike O’Leary, who calls Boston his hometown and cheers for the Bruins.

O’Leary is new to politics. He has many unexploited vulnerabilities.

He has a long track record of saying outrageous things on television, which his opponents are free to quote. He tried to neutralize the threat this week by saying that he was basically clowning around on TV — which makes sense to me, but may not to all Conservative supporters.

And he isn’t really a Conservative. He looks and sounds more like a middle-of-the-road, latte-drinking Toronto Tory than a rock-ribbed Reformer, something Westerners may find off-putting.

Quebec, which has a quarter of the votes, may be no easier for O’Leary. He doesn’t parlez vous, and the last unilingual anglophone to carry the province was John Diefenbaker.

If O’Leary is ahead on the first round, Leitch needs Bernier behind her to have any hope of leapfrogging Mr. Wonderful, so you can expect her to keep going after Max. If O’Leary is ahead on the first round, Leitch needs Bernier behind her to have any hope of leapfrogging Mr. Wonderful, so you can expect her to keep going after Max.

And critics have raised serious questions about his business practises — the basis of his appeal as a truth-telling businessman.

Still, O’Leary doesn’t have to prove that he’s the best leader the party could have. He only has to make the case that he’s better than the other choices. Conservatives in 2017 are in the same situation as the Liberals were in 2006: They don’t know who can lead them to victory.

This convention won’t play out like that one did (when the unlikely Stéphane Dion somehow emerged the winner) because the rules are different. Delegated conventions inevitably turn into game-theory exercises, with backroom arm-twisters figuring out how best to look after themselves.

The Conservative convention will be decided on a preferential ballot, and each of Canada’s 338 ridings — big or small — has 100 points, for a total of 33,800.

On May 27, Conservatives across the country will vote, marking each name in order of preference. When the votes are counted in Toronto on the Saturday, officials will redistribute the second-preference votes of the candidate with the least amount of support and count again, dropping one uninspiring would-be leader at a time, until one of the candidates has 16,901 points.

That means there can be no convention floor wheeling-dealing, with the second place candidate offering the fourth place candidate the Finance department in some future cabinet.

Whoever has the most support going in likely will win — that’s what typically happens in one-member-one-vote conventions. It’s also possible that a polarizing candidate — like, say, Leitch — could start out ahead and be passed by someone else when second choice votes are tabulated.

So if you’re a candidate, it’s going to be crucially important for you to get a few more votes than your closest rival if you think some of that rival’s supporters might have marked you as their second choice.

That’s why Leitch went so hard after Bernier during the Quebec City debate, and why she will keep doing so so long as she thinks he’s ahead of her.

If O’Leary is ahead on the first round, Leitch needs Bernier behind her to have any hope of leapfrogging Mr. Wonderful, so you can expect her to keep going after Max.

And the candidates in the back of the pack are likely starting to realize now that they can’t win if they don’t propose attention-getting policies — and attack their opponents.

The race has been alternately diverting and sick-making. It’s about to get more intense.

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