Francois Legault, once a staunch proponent of sovereignty, accused Parti Québécois Leader Pauline Marois on Wednesday of allowing Quebecers to be plunged "into a ravine by caribou" — a reference to separatist hardliners who want another referendum.

The leader of the Coalition for Quebec's Future seized on a PQ initiative he said allows the introduction of citizen-driven referendums — including one on sovereignty — if 850,000 Quebecers sign a petition calling for one.

"So if the caribou take us into the ravine, you're going to say 'Yes,"' Legault told his former PQ cabinet colleague in their televised debate ahead of the Sept. 4 election.

Marois, who has been constantly vague on the timing of the next referendum, repeated her classic plebiscite line.

"I am a responsible woman," she said. "I have convictions and I am going to defend them. There will be a referendum when the Quebec population wants a referendum."

Marois also denied the government would be obliged to hold such a vote even if 850,000 people signed a petition.

In her post-debate news conference, Marois sought to clarify her position by describing a petition-driven referendum as "consultative."

"There is a latitude that the government could establish," she said.

"What I would prefer — and it will be debated as we discuss the legislation on citizen-initiated referendums — is that we be rather more demanding. In my mind, there has to be signatures from every part of Quebec. They couldn't be concentrated only in Quebec City or Montreal. But it would remain a consultative referendum."

Marois, like most PQ leaders in the past, has to walk a fine line: she must take into account opinion polls suggesting most Quebecers don't want a referendum, while she also has to placate party hardliners who have a habit of eventually eating their moderate leaders.

Legault, a hardline sovereigntist when he was a cabinet colleague of Marois between 1998 and 2003, says he will not hold a referendum for 10 years and that he would even vote No if one were held right now.

There appeared to be no love lost between the two during the debate as they constantly interrupted one another with the moderator allowing them to proceed.

Marois was to make a run for the PQ leadership in 2001, but backed out after being abandoned by none other than Legault, who threw his support behind Bernard Landry.

Earlier in the debate, Legault got off one of the best one-liners of the night when he dubbed Marois the "queen of the status quo."

He said he would slash bureaucracy if he became premier, including cuts to Hydro-Quebec and in the education sector. At the same time, he accused Marois of being beholden to Quebec's powerful unions.

"You are the queen of the status quo," Legault told his former PQ ally. "It's sure that nothing will happen with you (in power). Both your hands are attached to the unions. No positions will be abolished... It will be the status quo."

In a later exchange, when Legault told Marois that the only debt that interested her was the debt toward unions, the visibly irritated PQ leader replied: "You're really obsessed. I can't believe it."

PQ, CAQ leader both promise integrity

The two politicians opened the televised tussle by each promising integrity if they become premier.

Their clash was the last of four consecutive debates featuring the province's political leaders and included four topics: governance, social policy, the economy and the national question.

Marois kicked off the highly anticipated encounter by telling Quebecers a PQ government would be clean.

"You have in front of you two very different visions of Quebec," she said. "My vision is to present an honest and responsible government. And we are going to do that with Quebecers."

With corruption a hot-button issue in the campaign, Legault didn't want to let his PQ rival occupy centre stage on the topic.

"I think what Quebecers want is a clean and efficient government that stands up to interest groups," Legault told viewers. "The priority in Quebec is a major cleanup to get rid of corruption and waste."

The previous head-to-head debates this week saw Marois duelling with Liberal Leader Jean Charest on Monday, and Charest duking it out with Legault on Tuesday.

There was a four-leader debate on Sunday.