The thorny issue of sovereignty re-emerged on the Quebec campaign trail on Sunday, as Liberal Leader Philippe Couillard suggested his Coalition Avenir Quebec rival hadn't totally given up on the idea of an independent Quebec.

With just over a week remaining in the campaign, Couillard questioned Francois Legault's federalist leanings, suggesting the former Parti Quebecois minister hasn't changed his stripes despite Legault's emphatic promise to never hold a referendum.

"He even said, some time ago: 'I'm not talking about (sovereignty) because the numbers aren't there,'" Couillard said in Vaudreuil, about half an hour west of Montreal.

"Does that mean that if the numbers change he will be in agreement again? You have to ask him the question."

Legault completely rejected the suggestion of his rival, who he accused of dusting off "the referendum scarecrow" out of desperation.

"The only referendum (question) is, 'Do we want 19 years of the Liberal party?" he said in Gatineau, Que.

"We've had 15 years, do we want another four years? Quebecers have turned the page on sovereignty, especially the youth."

On Saturday, Quebec's political party leaders largely put partisan politics aside as they gathered in Gatineau to express their solidarity for the victims of the tornado that devastated Canada's capital region.

That cameraderie appeared to have largely dissolved on Sunday, as Couillard criticized not only Legault but also Quebec solidaire's Manon Masse, whose promises he described as unrealistic.

Masse, whose party has been gaining in the polls, also found herself in the crosshairs of Parti Quebecois Leader Jean-Francois Lisee, who accused Quebec solidaire of "manipulating the electorate" and hiding the identity of its true leader.

Lisee doubled down on a criticism of Quebec solidaire's leadership structure that he first made last week during the final leaders' debate.

The smallest of the parties represented in Quebec's legislature has no official leaders but has Manon Masse and Gabriel Nadeau-Dubois as co-spokespeople.

But because Quebec's election law requires the appointment of a leader, they chose to list its general secretary, Gaetan Chateauneuf — leading Lisee to suggest it's he rather than Masse who is pulling the strings.

On Sunday, Lisee accused the party of having both a "hidden leader" and a hidden agenda that he said would includes nationalizing Quebec's large industries.

"When we have a co-spokesperson who says she has power when we know that's false, it's manipulation," he said.

Quebec solidaire held three of the 125 seats in the legislature ahead of the campaign.

While it has been polling in fourth place, the numbers suggests the small sovereigntist party could win more seats on Oct. 1 — especially in the Montreal area, where the Liberals and Parti Quebecois have traditionally dominated.

Meanwhile, as Legault rejected the Quebec sovereignty option on Sunday, Masse embraced it as a necessary means to secure the province's environmental future.

At a news conference, she outlined her party's plan to separate from a "pro-oil" Canada, which would include allowing Quebec's finance ministry, rather than the party, to set the province's budget for the first few years.

She also responded to Lisee's criticism of her party's agenda with a brief video statement published on Twitter.

"Quebec solidaire wants to transform the economy, wants to transform Quebec, and wants to make the necessary revolution of the energy transition," she said.

"I'm not hiding anything."

-- With files from Julien Arsenault in Vaudreuil, Que, Stephanie Marin in St-Jean-sur-Richelieu, Que. and Melanie Marquis in Gatineau