The Coalition for Quebec's Future leader didn't mince words as he entered a post-election caucus in Dummondville on Thursday.
Legault, a former PQ cabinet minister, said his old party will have to go through the same kind of reflection he did when he quit the PQ caucus and left politics in 2009.
He pointed out that at least 70 per cent of Quebecers have said they don't want another sovereignty referendum, leaving the PQ without a viable issue.
Legault described the PQ as being in a dead end and invited its members to join the Coalition, which he called an example of modern nationalism.
He said such PQ hardliners as Jean-Francois Lisee, Bernard Drainville and Pierre Karl Peladeau, who are all considered potential PQ leadership candidates, would be welcome in the Coalition.
However, Legault added that Peladeau would have to sell his majority shares in media giant Quebecor before he could make the switch.
The PQ was to choose an interim leader later in the day following the resignation of Pauline Marois on Monday night.
The Coalition increased its seat total in the legislature by three in Monday's election, going from 19 to 22.
The Liberals under Philippe Couillard won a majority government with 70 seats of the 125 seats up for grabs.
The PQ came in second with 30 seats.
Quebec solidaire maintained its fourth-place status but increased its members in the legislature by one for a total of three seats.
Legault says he understands that the PQ has a difficult challenge.
"The PQ has to go through the same reflection I did in 2009," he said. "Article 1 (of the PQ platform) is sovereignty and people don't want a referendum.
"There are a lot of members who are only in the PQ because they want a referendum. For me, it's not an issue."
With so much opposition in the general public against a referendum, Legault suggested the sovereigntists have to be practical.
"Without an issue, what are the chances of forming a government," he said. "What's the solution? I didn't find one so I decided to form a new party."
He didn't think Lisee, Peladeau and Drainville would have any better luck figuring out what to do with the PQ.
"They're welcome in the Coalition," he said.
Legault said the Coalition will be looking at how to shore up their organization in the regions in the wake of the strong Liberal showing across the province.
He acknowledged his party has to beef up its ground game with a strong team of volunteers if it hopes to make gains in the next election in 2018.
While the Liberals were kicked out of office by a slim margin in 2012, it is generally acknowledged that they mounted a formidable effort in getting out the vote on Monday night.
"I'll be honest," said Legault. "It's certain that in the regions, we have a challenge with organization, mobilizing supporters and recruiting volunteers to get out the vote."
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