MONTREAL -- Ambiguities on the independence question were seized upon as buoys Thursday by a Charest Liberal campaign that had earlier seemed adrift.

The Liberals latched onto that familiar lifeline as their two main opponents struggled with questions about inconsistencies on the one issue that has defined Quebec politics for decades.

The Parti Quebecois explained that, contrary to what it told members months ago, citizens would not be able to automatically initiate a sovereignty referendum by raising enough signatures on a petition.

Pauline Marois explained that her party would only consider the possibility of a referendum once 850,000 signatures had been gathered.

"It will force a government to reflect deeply," Marois said of the petitions demanding a plebiscite. "Ultimately, it's up to the national assembly to decide when there will be a referendum."

She was forced to clarify that position after coming under fire in her TV debate with her old colleague, and current foe, Coalition party Leader Francois Legault.

But Legault was peppered with questions about his own ambiguous position on the independence question, such as: If he became the opposition leader, and the PQ called a sovereignty vote, what side would he campaign on?

The province's referendum law gives parliamentarians five days to join either the Yes or No side. If one side has no leader, the province's elections body is responsible for finding one from the general public.

Legault explained that he would not join either side in a referendum. Until then, he'd do everything to avoid one, he said, "We will fight against having a referendum. We don't want a referendum."

Legault's position on the national question, as expressed in the last few days, is as follows: He doesn't want a referendum. If there were a referendum, he'd vote No to independence. He wouldn't participate in that campaign. However, he also says it would be bad for Quebec if it "lost" the referendum in a No vote -- an analysis he voiced during Wednesday's TV debate.

That ambiguity prompted a scolding from Liberal Leader Jean Charest.

"The moment there's a conflict on the (national question) he'll be missing in action," Charest said of Legault.

"Seats in the national assembly aren't spectators' chairs... They're not VIP seats to watch political debates."

He also poked fun at Legault's ambivalence. Charest noted at a news conference that the event Thursday was being held near Montreal's main airport.

"It must be interesting when Francois Legault passes through customs. They ask him for his citizenship and he says, 'I'm neutral.' Are you Canadian? 'Oh, no, no, no, hey, I'm not Canadian.' Are you Quebecois? 'No, no, no, no. I'm neutral.' "

Charest joked that, even if he hadn't been a participant in the previous night's debate, "I believe I had a very good debate yesterday."

The leaders of Quebec's main political parties were back on the hustings Thursday hoping televised debates might give their respective campaigns a massive boost.

The would-be premiers have just less than two weeks left to impress Quebecers before the Sept. 4 election.

Marois was perceived as the campaign's front-runner before the various debates began last Sunday, but it is unclear how the encounters have influenced voters.

The latest details about the Coalition and PQ positions on independence only emerged after Wednesday's final debate, between Marois and Legault.

The PQ also came under attack during the debates for not having released the costing of its campaign promises. The party promised Thursday to release the fiscal framework on the weekend, then pushed the date up a day and now says it will happen Friday.