Sunday's rally was in enemy territory for the Liberals: the NDP stronghold of Hamilton Centre, where for the second time this campaign, Justin Trudeau brought out a former Prime Minister to boost his own brand. Today it was Jean Chretien helping Trudeau fire political bullets at his opponents.

Together, they both attacked Mulcair, who insists a simple majority, 50 per cent plus 1, is enough to start negotiations on separation. Mulcair has also promised to rip up the Clarity Act, which became law in 2000 after the 1995 razor-thin Quebec Referendum, while Chretien was in power. The Act is based on a Supreme Court of Canada Reference that stipulates any vote must have a "clear majority."

Chretien and Trudeau both said Mulcair's threshold was not responsible.

"Mulcair and the NDP believe all that's required to break up this federation we have worked so hard to preserve for nearly 150 years is a single vote," Trudeau said.

He avoided -- again -- providing a threshold of his own, only saying "the actual number is to be determined in the context of the next referendum." According to the Act, it's the House of Commons that determines if there has been "a clear expression of a will by a clear majority of the population."

By bringing out Liberal Party elders like Paul Martin (who trumpeted his government's record on the economy) and Chretien, Trudeau wants to show that he is supported by an established team -- even if he himself may lack the experience of his opponents.

Another part of the strategy, in such a tight race, could be about finding a wedge issue that will allow Trudeau to break way from the pack.

But with the separatist movement on life support and Bloc Quebecois severely diminished, will the Quebec separation issue be the issue that does that? Will it resonate with voters? Right now, there appears to be other, more dominant themes: the economy, the Syrian Refugee Crisis, Mike Duffy and the PMO.