OTTAWA -- The prospect of an NDP surge has parties going back to their electoral calculators to determine if it might cost the Conservatives a few seats -- or give them the most crushing majority in a quarter-century.
Or maybe a bit of both.
The reality of the riding-by-riding breakdown is that the Tories could lose a few close races while still coasting on an orange wave all the way to their coveted majority.
That unpredictability was reflected in seat projections Friday that offered a wild range of potential outcomes, with the Tories being pegged to win anything from a smaller minority to a whopping 201-seat majority.
The uncertainty is also reflected in Prime Minister Stephen Harper's itinerary. He will begin the day today in Toronto, where a stronger NDP showing could help him, and end it in B.C., where it could cost him an existing seat.
Even the Conservative attack ads are getting less predictable. The party released a spot Friday focusing on New Democrats for the first time in this campaign, but also announced ad buys targeting its more traditional foes -- the Liberals and Bloc Québécois.
The NDP spot is similar in substance and tone to older Tory attacks on the Liberals' Michael Ignatieff. Black-and-white images of NDP Leader Jack Layton and Bloc Leader Gilles Duceppe are set among shadows in the Tory ad as a sneering narrator intones that the NDP chief is driven by blind ambition.
The New Democrats held a news conference in Ottawa to respond to the Conservative ad, demanding it be yanked because it is based, in their view, on false information.
But the NDP's gain in popularity may also be the Conservatives' gain. A big turnout of New Democrat voters could split the left-of-centre vote, says a veteran pollster, allowing the Tories to sneak up the middle in a number of ridings.
Harris-Decima chairman Allan Gregg says that in general, the NDP is the second choice of most Liberal voters. "So in aggregate, if the Liberals go down, New Democrats go up," Gregg said.
"So it's probably, in aggregate again, in the Conservatives' best interest to support or cheer-lead for the New Democrats, because their rise in support will come disproportionately from Liberal voters."
He cautions that doesn't hold true everywhere. The NDP runs second to the Conservatives in some B.C., Prairie, Ontario and Atlantic Canada ridings.
Hence Harper's stop Saturday in B.C's Vancouver Island North riding, held by Conservative John Duncan, who faces a threat from NDP candidate Ronna-Rae Leonard. Another New Democrat challenger finished a close second against Duncan in the 2008 campaign.
Nowhere is the NDP's newfound popularity more surprising than in Quebec. That's partly because some of the Bloc's soft nationalist vote is bleeding to the New Democrats. Some polls even put the NDP -- for the first time ever -- in first place in that province.
Bloc Québécois Leader Gilles Duceppe warned voters in his province not to be drawn in by Layton's smile. Duceppe, usually a friendly ally of Layton's in Parliament, cranked up his attacks on the New Democrat as someone who is out of touch with Quebecers on many issues.
"I am inviting Quebecers to reflect, to discuss this and look beyond the image, to not vote for a mirage, but for a party, the Bloc Québécois, that is the mirror of Quebec society."
Layton shot back while campaigning in Toronto: "We won't give up. We will continue our efforts to demonstrate that people have a real choice."
All federal parties appear worried they might pay a political price if the NDP continues its rise in the polls.
The Liberals, who have consistently tried making this election an either-or struggle between them and Stephen Harper, now have an added obstacle on their path.
One Conservative source says his party would stand to make gains from an NDP rise. The latest trends certainly have the hearts of some Tory supporters beating orange.
One need only glance at the Twitter website for signs of a Layton love-fest among Conservative backers, though the party itself is offering no such kudos through official channels.
"Mr. Layton's reward for running an ideas-based campaign," former Tory staffer Yaroslav Baran wrote after a recent poll put the New Democrats ahead of the Liberals.
"Gotta say, 'Opposition Leader Jack Layton' is a rather intriguing and politically reinvigorating concept," he tweeted later.
Opined Conservative blogger Stephen Taylor: "Imagine: Jack Layton as leader of the opposition. Would give Liberals a much- needed timeout to finally rebuild their party."
But it's not just across the Twitterverse and blogosphere that Layton is suddenly popular with those on the political right.
Layton appeared as a guest during the first week the conservative-leaning Sun News Network was on the air. Twice this week, the Sun newspaper chain splashed an orange banner across the front page of its Ottawa edition, featuring photos of the NDP leader smiling and waving.
Meanwhile, voting began Friday at advance polls where people could cast their ballots early.
-- The Canadian Press