Alas, Americans don’t pay much attention to politics in Canada, our most reliable ally. That might change Monday night when returns roll in from the Canadian election. If the polls are right — and there are a lot of “ifs” — our friendly neighbor to the north is brewing a political revolution.

The big news out of Canada is that North America’s largest social democratic party — that would be Canada’s New Democratic Party, or NDP — threatens to displace the centrist Liberal Party as the country’s main opposition. Even more astonishingly, the NDP has an outside chance of winning the most seats in the election.

When the campaign started, the likeliest outcome was that Prime Minister Stephen Harper’s Conservative Party would win again, probably with a minority of seats in Parliament, but with a real possibility of securing a majority.

The Liberals, the Conservatives’ traditional challengers (and, until recently, the natural governing party in Canada) were not seen as likely to win, but they did have real hopes of recovering after a disastrous election in 2008, when they lost 26 seats in Canada’s 308-member Parliament.

At the beginning of the campaign, the Liberals’ new leader, Michael Ignatieff, got high marks from the media for running an open, friendly and informal campaign. An academic and human rights campaigner who spent years in the United States, Ignatieff surprised many people with how good a campaigner he had become.

But the Conservatives had roughed Ignatieff up with a tough pre-campaign advertizing blitz, and they continued to hit him hard after the opening gun was sounded. In the meantime, NDP leader Jack Layton proved the perfect match for the moment with a kind of low-key charisma and a campaign rooted in a promise to shake up Canada’s political system. The NDP is a long-time third party in Canada, with an appeal rooted in the unions and in left-populist sentiment on Canada’s prairies. But Layton expanded his party’s appeal from its base to a broad middle ground that seems turned on by his energy and the possibility of something entirely new.

Key to Layton’s breakthrough has been his appeal in largely French-speaking Quebec. Canada has what you might call a three-and-a-half party system. Besides the Conservatives, the Liberals and the NDP, there is also the Bloc Quebecois, which runs only in Quebec and represents nationalist and separatist sentiments in the province. (There is also a Green Party, but the NDP’s strength seems likely to limit its vote this year.) The Bloc usually wins the most seats in Quebec, and it does especially well when Quebeckers feel that their interests and their cultural values are threatened by the rest of Canada.

But Quebeckers feel no such threat this year. And Layton, who hails from Montreal, has picked up a lot of “soft nationalist” votes from Quebeckers who have doubts about separation but some sympathy for the idea. The NDP now threatens to outpoll the Bloc in Quebec.

This morning’s Globe and Mail has a good summary of where the contest stands now, citing results from the Nanos polling firm:

With only three crucial campaigning days left, Jack Layton and the NDP continue to close the gap on the Conservatives, narrowing Stephen Harper’s advantage now in key battlegrounds of Ontario and British Columbia, according to the latest Nanos Research survey.

Given the slim five-point lead for the Conservatives nationally, the NDP and Liberals could win more seats combined than the Tories on May 2 with a “rump” separatist party holding the balance of power, pollster Nik Nanos says.

The numbers from the poll are remarkable:

The three-day tracking poll shows the Conservatives with 36.4 per cent support compared to the NDP with 31.2 per cent, up slightly from the day before. The Liberals are at 22 percent, the Bloc is at 5.7 per cent nationally and the Green Party is at 4 per cent.

While the NDP continues to dominate in Quebec — 41.4 per cent support compared to 23.6 per cent for the Bloc, 16.1 per cent for the Liberals and 15.8 per cent for the Tories — the story in Ontario is changing.

The NDP is continuing to increase its support in the seat-rich province while the Conservatives continue to drop. Overnight, the New Democrats have grown their support to 28.5 per cent from 26.1 per cent.

         Predictions are especially vexed in a three-and-a-half way race. In Quebec, the NDP, the Liberals, and the Bloc could split the anti-Conservative vote in ways that allow Harper’s party to pick up seats with a relatively small share of the vote. Elsewhere, especially in Ontario, the rise of the NDP could be enough to take votes away from Liberals but

not enough to beat the Conservatives in close ridings, as the Canadians call their parliamentary districts. Harper’s best hope is that such splits allow him to win more seats than his overall share of the national vote would suggest he might. If the splitting of the opposition gets really strange, Harper might yet get close to a majority.

       Still, that’s mostly a caveat, if an important one. The big story is the NDP’s breakthrough and the fact that it is now threatening the Conservatives. The New Democrats are the only party with real momentum right now.

       Personally, I feel badly for Ignatieff, whose work I have always admired. His biography of the philosopher Isaiah Berlin is masterly, and everyone who cares about justice and human rights should read his book The Needs of Strangers. But progressives south of the border can learn some lessons from the rise of Layton and the NDP. In a period when parties of the democratic left have not fared all that well in the wealthy democracies, the NDP is poised to deliver some good news.