Faced with the alarming threat of surging support for the NDP, Liberal Leader Michael Ignatieff is now accusing the social democrats of making tens of billions of dollars worth of promises that they have no means of paying for.
"It's time to take a close look at what Jack Layton is saying to the Canadian people," the Liberal Leader told reporters in Halifax Saturday when asked if he was now in a race for second place.
"The numbers add up. And up. And up. And up," Mr. Ignatieff said, referring to the NDP platform.
While Liberal promises were fully costed, he went on, "Mr. Layton has got a platform which, when you look at it closely, has $30-billion in spending, which we think is not going to be good for the economy, and he derives it from sources we just don't think are credible."
Mr. Ignatieff is pivoting to protect his left flank, as several recent polls show the NDP approaching or even surpassing the Liberals in support with only eight campaigning days left until the May 2 election.
Those poll results have also prompted both the Liberals and the Harper Conservatives to redirect their air attack at the NDP leader, with the Tories are re-airing ads slamming the role Jack Layton played in assembling the 2008 coalition with the Liberals.
The Grits have debuted a new ad accusing the NDP of failing to support the gun registry - some NDP MPs did vote unsuccessfully to scrap it - and of making unaffordable spending commitments.
The ad also accuses the party of having "incredibly inexperienced candidates."
"Not so fast, Jack," the narrator warns, as a stoplight turns red.
The Liberals point out that the NDP platform envisions rather magical sources of funding, including from a cap-and-trade system to limit industrial greenhouse gas emissions that would take years to set up and may end up costing governments more in lost business taxes than they ever raise in revenue.
Mr. Layton deflected the criticism following a packed Montreal rally Saturday afternoon.
"The Liberals have said they want to do cap-and-trade too, so I don't understand their criticism," the NDP Leader said, pointing to similar systems in U.S. states as models that Canada could quickly adopt.
"It's a matter of political will and that's what lacking."
By taking on the NDP, Mr. Ignatieff pays a price in three ways. First, every minute and dollar spent pointing out the contradictions embedded within the NDP platform is a minute and dollar diverted from the effort to close the yawning gap between the Liberals and the front-running Conservatives under Stephen Harper.
Second, accusing the NDP of making reckless promises that could damage the economy and wreck government finances simply echoes the criticism that the Conservatives level at the Liberals.
Finally, and most importantly, the more Mr. Ignatieff takes on Mr. Layton, the more he renders the NDP chief credible as a potential leader of the official opposition.
This comes as opinion polls suggest major growth in support for Mr. Layton in Quebec, an uptick Conservatives privately say could also be at work in British Columbia. The data, which shows the Tories still far ahead of the Liberals, has raised the question of whether the NDP could supplant the Grits as Official Opposition in Ottawa.
An Ipsos-Reid poll taken April 18 to 20 suggested the NDP has bumped the Liberals out of second place nationally and that the Tories were on track for a majority government in the May 2 election. This is the first time in two decades the NDP is ahead of the Liberals in polls.
"Something is going on in Quebec - a wind of change, change that you can feel blowing all along the St. Lawrence River," Mr. Layton told the crowd at Saturday's Montreal rally, which was held in the heart of the downtown riding held by Gilles Duceppe for two decades.
But the Liberals believe that dashing some cold water on the voters' sudden infatuation with the NDP is worth the political risk involved.
"We can form the next government," Mr. Ignatieff reminded voters. "Repeat that word: government."
But few believe that Liberals have any prospect, now, of winning the most votes and the most seats on May 2. Mr. Ignatieff's only, and increasingly waning, hope is to limit the Conservatives to a minority government, bring that government down, and then form a minority government with the support of the NDP.
But unless voters retreat from their flirtation with Smiling Jack Layton in the last week of the campaign, it's not exactly clear who would be supporting whom.
On Saturday, the Conservatives modified their campaign script where they warn that if the Tories don't get a majority government they will be unseated by a coalition of opposition parties.
Now the Tories are suggesting this coalition they fear could even be led by Mr. Layton, a messaging chance that showed up in the introduction at a Harper campaign stop in Mississauga given by area Tory candidate Bob Dechert.
Mr. Harper, speaking after his Missisauga address at a Coptic Christian centre, said it doesn't matter if the NDP or the Liberals are the leading opposition party.
"The fundamental choice has not changed," he said.
He said the only options are a Conservative majority or a government that's "a combination of the Liberals, New Democrats and the Bloc."
Liberal Leader Michael Ignatieff has flatly refused to form a coalition with other parties. But he has said it's possible the Liberals could take power even if they win less seats than the Conservatives but can reach some accommodation with rivals in the Commons.