OTTAWA -- After a dramatic campaign that threatens to remake national politics, Canadians will decide today whether to give the Conservatives their much-coveted majority government and a mandate to govern unimpeded by the opposition parties.
But a campaign that began in March ends in May with that Conservative majority in doubt, the centrist Liberals in retreat, and the separatist Bloc Quebecois in a free fall. The story is the stunning rise in popularity of the left-of-center New Democratic Party, which has surprised the pollsters and confounded the professionals.
In fact, Canadians may awaken tomorrow to a realignment of their politics.
It could mean the end of the Liberal Party as a force in national politics or the prospect of a coalition of New Democrats and Liberals unseating the Conservatives, who have held a plurality of seats in a fractious Parliament since 2006.
Although the Conservatives could get a majority, the polls suggest they will remain in office with some 140 of the 308 seats in the House of Commons, 15 short of the necessary 155. But they are likely to face the New Democrats as the official opposition -- a turn of events not even the most fervent partisans would have predicted for a fringe party committed to a European-style social democracy, which never has held power in Ottawa.
On the eve of the election, though, the polls show the Conservatives running first, with 34 percent to 37 percent of the vote. The New Democrats are second with 27 to 30 percent. The Liberals are third with 20 to 24 percent, and the Bloc Quebecois are at 7 percent (concentrated in the French-speaking province of Quebec).
As the New Democrats have risen in the polls, the Liberals have fallen. If the results are as expected, the Liberals will record their worst showing (in terms of popular vote, if not in seats) in their history. Some predict that the party could disappear, like the Liberal Party in Great Britain in the last century, squeezed between the Conservatives and the New Democrats, as both try to claim some of the political center.
For the party that has governed Canada for most of its history and that has been one of the most successful political organizations of the last century, third place would be a disaster. Led by prime ministers Sir Wilfrid Laurier, Mackenzie King, Lester Pearson, and Pierre Elliott Trudeau, the Liberals were long called "Canada's natural governing party," representing an urban, progressive Canada. They were a national party, based in Quebec with support everywhere in the country, alternating between English and French leaders.
That legacy, though, is in danger under the leadership of Michael Ignatieff, a successful broadcaster, author, and academic who returned to Canada in 2005 to enter politics after teaching at Harvard University. He is struggling. "The most successful political party in the advanced western world of the last 50 years could be on a banana peel about to go into political oblivion. It's a real possibility," says Frank Graves, one of Canada's leading pollsters.
Mr. Graves says he thinks that the New Democrats could win 100 seats Monday. They had 37 seats when the election was called; the Liberals had 77, the Conservatives 143, and the Bloc Quebecois 47.
Neither Mr. Graves nor any other pollsters have an easy explanation for the sudden ascent of the New Democrats, who entered the campaign in third place, safely behind the Liberals. Some suggest Canadians are tired of incumbents, meaning the Conservatives, who hold power, and the Liberals, who have held power.
Others believe it is the appeal of the NDP leader, Jack Layton, the sunny former Toronto city councilman who has led the party for eight years. Mr. Layton was recovering from prostate cancer and hip surgery when the campaign began and still walks with a cane. Faced with a choice of Stephen Harper, the dour former economist, and Mr. Ignatieff, the aloof intellectual, the electorate has warmed to Mr. Layton. His popularity particularly began to rise after the campaign's two televised debates, in which no candidate won but Mr. Layton showed well.
The story of the party's rise, though, is in Quebec, where the NDP now has only one of 75 elected representatives. Since 1993, the left-of-center Bloc Quebecois, which wants to make Quebec an independent country, has controlled most seats in the province, the only one where it runs candidates.
The conventional wisdom was the Bloc Quebecois would win most of the seats in Quebec this time, as it has for the last five elections, leaving about a dozen each to the Conservatives and the Liberals. According to the polls, however, support for the Bloc has collapsed.
The Bloc is now in danger of losing most of its seats to the surging New Democrats. Quebeckers, more liberal than the rest of the country and tired of talking about independence, like the New Democrats' policies on social welfare and the environment, as well as their openness to Quebec's traditional demands for more constitutional powers within Canada.
For Mr. Harper's Conservatives, who have campaigned for a majority to preserve Canada's economic and political stability, the surge in support for the New Democrats is a costly surprise. Not only could the Conservatives lose some of their seats in Quebec, the NDP is eating into their support in Western Canada. Although Mr. Harper's strategy was always to split the left-of-center vote for a small majority, he did not expect the New Democrats would do this well.
But three-way splits in many constituencies could produce any number of outcomes, including a Conservative majority with the party winning a little more than a third of the vote. It could produce a Conservative minority facing an alliance between the New Democrats and the Liberals, whom the prime minister has warned repeatedly would join forces to force him from office.
Canada's fourth election in seven years also could bring new leaders of the Liberals and the Bloc Quebecois, whose new weakness will sharpen ideological divisions in Parliament and threaten the tradition of moderation in Canadian politics.
Andrew Cohen is an author, syndicated columnist, and professor of journalism and international affairs at Carleton University in Ottawa.