With their political momentum apparently stalled, the New Democrats plan to launch a course correction, shifting their strategy with a recalibrated campaign that includes sharper attacks on Liberal Leader Justin Trudeau.

CBC News has learned that the NDP will be buying more broadcast ads in an attempt to reverse a recent sag in the polls.

Not only can Canadians expect to see more ads, but the NDP plans to intensify campaigning in the days ahead, which includes more touring in southwestern Ontario.

Tom Mulcair gets in a zinger as Justin Trudeau discusses the NDP's cap-and-trade system at the Munk debate on foreign policy. 0:32

This new strategy would move away from comparing NDP policy with the Liberal plans and instead highlight the issue of leadership — who would make the best prime minister.

The idea is to demonstrate Tom Mulcair is a stronger leader than Trudeau, to knock down his support a few points and to reduce the Liberal leader's likability quotient in English Canada.

Anti-Trudeau radio ads

To that end, the party has just launched a series of anti-Trudeau radio ads, which include attacking the Liberal leader over his support for C-51, the controversial anti-terrorism legislation that gives more power to Canada's security forces.

The other ads accuse Trudeau of being hostile to the auto and manufacturing sectors and slam him for charging thousands of dollars of speaking fees for appearances at school boards and charities.

The party has also seen its support decline in Quebec, a province where it's crucial for the party to at least retain its seat count for any hopes of a victory. The NDP believes it has been hurt by the so-called niqab issue and opposition to the Conservative government's ban on wearing the face veil while taking the Canadian citizenship oath. Polls suggest a vast majority of Canadians support the Tories on this issue, but the strongest support is in Quebec.

The party is hoping to turn the attention of Quebecers away from the niqab issue and back to what it sees as the most significant ballot question — whether Quebec voters want Conservative Leader Stephen Harper to remain as prime minister.

The NDP slide comes weeks after Mulcair kicked off his "campaign for change," running what many perceived as a traditional front-runner's race. Just last weekend, Mulcair was telling CBC's Chris Hall of The House that he was consulting with experts and preparing to form a minority government after the Oct. 19 election.

But recent polls suggest the NDP's political fortunes, especially the momentum it had in Quebec, has since softened.

After weeks of the Conservatives, Liberals and NDP in a virtual tie, the CBC Poll Tracker now shows the widest gap between first and third place since Sept. 8.

CBC polling analyst Éric Grenier says the numbers show the NDP slipping to the third spot behind the Liberals, whose support appears to be holding steady. He said voters who are more concerned about defeating Harper than they are for voting for the party of their choice could decide to flock to the Liberals.

The cause of the softening of support may be hard to discern. Mulcair has been critical of the Clarity Act legislation that calls for a "clear majority" result if Quebec were to vote on secession. Instead, he has championed the NDP's own unity bill that would recognize a referendum victory by the yes side, even if it were by a majority of 50 per cent plus one, a position that presumably would gain him support among sovereigntists.

Opposition to ISIS mission

He has also opposed Bill-C51 and Canada's military mission against ISIS in Iraq, which involves airstrikes and training local ground troops. Mulcair has vowed to bring home all Canadians from that mission.

On the first issue, Mulcair is likely on side with many Quebecers, but it's unclear if his opposition to the ISIS mission is also resonating in the province, which traditionally shows the least support for military action. Indeed, Bloc Québécois Leader Gilles Duceppe has come out strongly in support of military intervention.

Although Mulcair's opposition to the Conservative ban on the niqab may have hurt the NDP's standing in Quebec, it's not clear why the issue hasn't also affected Trudeau, also an opponent to the ban, who has arguably been more vocal about it.

It's possible that Mulcair has been stung by repeated criticisms from both Trudeau and Duceppe that Mulcair is a political opportunist and has flip-flopped on a number of issues. Both claim that Mulcair takes one position for a Calgary audience and another while speaking in Quebec, a charge Mulcair has denied.

But the drop in support may also suggest that the Orange Wave that took hold in Quebec and propelled Jack Layton into the role of the Official Opposition leader was built in large part to Layton's personality, something Mulcair has been unable to replicate.