Forget about the two solitudes. Montreal Mayor Denis Coderre says he wants Montreal and Toronto – leading centres of French and English Canada, and great rivals for generations – to become sister cities.

He says that the two need to work together on solutions to common urban problems. Together, he says, they may have more luck persuading Ottawa to take cities seriously.

"The two solitudes are over," he told the media on Wednesday after meeting Toronto Mayor John Tory at City Hall. "Clearly, the time has come that the metropolis of Quebec talks to the metropolis of Canada," he added later at a lunchtime talk to Bay Street heavyweights.

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He called for a "strategic alliance" between the two. Asked if that meant making them sister cities, he said that it would.

Sister-city deals are nothing new. Mayors make them all the time and they usually amount to little more than symbolism and platitudes.

But when Montreal and Toronto talk sisterhood, something more interesting is happening. The two cities are historic competitors in sports – Leafs versus Habs – and in many other things. It was a milestone in the life of the country when Toronto surpassed Montreal in population and became its main economic hub.

The divide between them has always seemed much wider than the six-hour drive would indicate. Many Torontonians never make the trip, many Montrealers wouldn't think of it. Montreal's French-speaking intellectual elite looks to Paris, Toronto's elite to New York.

But times are changing. The separatist cause is faltering. Quebec has a new, pragmatic, federalist Premier in Phillipe Couillard. Mr. Coderre, a Liberal MP and cabinet minister for 16 years before Montrealers elected him mayor in 2013, seems cut from the same cloth. He is energetic, funny, open-minded and bursting with fresh ideas.

The Toronto-Montreal sisterhood is one of his freshest. Mr. Coderre notes that Canada's two biggest cities have loads in common. Both have diverse populations fed by heavy immigration. Both are struggling to fix crumbling infrastructure. Both are trying to find the money to build out their transit networks.

"We always joke about the confrontation and competition between Montreal and Toronto," he said. "And people, what they are expecting now, they want answers. They want to make sure we're getting over all those old arguments and let's focus on the future."

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He can see the two cities making a joint pitch to the federal government for more infrastructure funding. He can see them comparing notes on how they cope with problems such as homelessness and shortages of public housing. He can even see travelling out of the country with Mr. Tory to drum up investment in their cities. In the longer term, he wants to work with Mr. Tory and other mayors to get more powers for city governments, freeing them from their status as creatures of the provinces.

Will all of this sisterly sentiment lead anywhere? For now, it is mostly talk. "Building a strong Montreal and a strong Toronto is about building a strong Canada," Mr. Tory said when the mayors met the press on Wednesday. Now who could argue with that? But given the traditional alienation between these two great cities, the fact that they are talking is encouraging all the same.

Under Mr. Tory, Toronto is moving past the embarrassing mess of the Rob Ford era. Under Mr. Coderre, Montreal is moving forward from the corruption scandals of recent years. Here are two clever, charged-up, forward-looking mayors who want to work together to make their cities better. Cities, says Mr. Coderre, are where you encounter many of society's worst problems, but they are also laboratories for solutions.

In case their mutual admiration seems too cloying, there are still a few hints of the old rivalry. When a questioner, talking about tourism, tells Mr. Coderre that Toronto doesn't have enough "sexy" attractions for visitors, Mr. Coderre shoots back deadpan: "We don't have that problem."