Stephen Harper is shifting his game plan after a singular focus on damaging his Liberal rival in the first four weeks of the campaign allowed NDP Leader Jack Layton to emerge as a serious challenge.
On Wednesday night, the Conservative Leader launched his sharpest attack so far on Mr. Layton, warning voters not be lured astray by "smiles and snake oil" and offering dire warnings of the damage the New Democrats might do to Canada.
Heading into this election, a big concern among Conservatives was that support for the NDP was too weak to damages the prospects of their main concern: Liberal chief Michael Ignatieff.
Four weeks later, with polls suggesting the NDP is now in second place nationally, the Tories now worry that Mr. Layton's vote is too strong.
The unexpected growth in support for the New Democrats has clouded the chances that Mr. Harper will win at least 155 seats to get a majority, partly because the Tories and NDP are direct competitors in many ridings across Canada.
With four days left on the hustings, the Conservative Leader has ramped up attempts to stop Mr. Layton's NDP, which is leading in Quebec and rising in B.C., burgeoning support that threatens to spill over into Ontario.
The Conservative campaign has devoted an increasing amount of effort this week to ridings where their biggest rival is the NDP, including northern Vancouver Island, Sault. Ste.-Marie, Windsor, and, on Wednesday night, the Niagara region riding of Welland. On Thursday, Mr. Harper heads to Quebec, where the NDP is running first in the polls.
In Welland, a seat that includes part of St. Catharines, the Tories are targeting New Democrat incumbent Malcolm Allen, who won his seat in 2008 by a few hundred votes. Conservatives are hoping to harness rural anger over the fact Mr. Allen changed his position last September and opposed a Tory effort to kill the long-gun registry.
Speaking to reporters Wednesday, Mr. Harper rejected the notion that the lift for the NDP is a repudiation of his core campaign strategy: warning voters the opposition parties would destabilize Canada by forming a coalition among themselves to oust a minority Tory government.
The only difference now, Mr. Harper said, is that Mr. Layton might lead the coalition.
During his Wednesday night rally in St. Catharines, Mr. Harper mentioned the New Democrats or Mr. Layton more than 16 times in 25 minutes - and for the first time this campaign, brought up the NDP's record of governing Ontario in the early 1990s.
"Get the big decisions wrong and it will take a generation to dig ourselves out," he said.
"I don't have to remind you what it took here after an NDP government in the province of Ontario. You don't need that, we don't need that."
Mr. Harper said the left-leaning party's surge to second-place in the national polls gives Canadians a starker set of options at the ballot box.
"The fact the NDP may be the leading opposition party actually clarifies the choice," he told reporters at a campaign stop in Kitchener, Ont.