The former media baron's candidacy has echoes of the last election in the province.
In the opening stages of the 2012 campaign, the announcement that renowned corruption fighter Jacques Duchesneau would stand as a candidate for François Legault's Coalition Avenir Québec marked a turning point.
With the CAQ floundering in the polls, Duchesneau's willingness to align himself with Legault's party signalled the CAQ was a real alternative to the Liberals and PQ. Corruption was the issue of the day, and Legault had landed one of the most credible anti-corruption figures in the province.
Though the CAQ came up short when the votes were counted, they still managed to take 27 per cent and place just five points behind the PQ.
Péladeau's candidacy marks a similar turning point in the campaign for Marois, though her party was already in a strong position.
Polls conducted before Sunday's announcement suggested the PQ and Liberals were neck-and-neck in popular support. But due to the PQ's advantage among francophones, the party could be expected to form government.
Péladeau gives the PQ a much-needed boost as the campaign kicks off. Despite its enviable position in the polls, the party was more likely to shed support as the election dragged on rather than pick up new voters. The PQ was already polling at its highest level in years.
Péladeau should help Marois stabilize that support, and perhaps pick off a few votes from the parties to her right.
The Parti Québécois has always been a coalition of sovereigntists from right and left. This has been both a strength and weakness.
It gives the party the ability to appeal to left-wing artists and intellectuals, unions and the working class, as well as rural conservatives. But it also means the PQ is often pulled in different directions from within, especially when things are going badly.
Péladeau is a good example of the contradictions within the PQ's coalition. The party has traditionally received support from Quebec's unions, yet Péladeau is seen in a very negative light in labour circles.
The PQ has rarely been seen favourably within the business community in Quebec, yet Péladeau is arguably the most successful businessman in the province.
His candidacy is a double-edged sword for the PQ, but the pros outweigh the cons. He could cost the PQ some votes on the left, which will go to Québec Solidaire. But he has a greater potential to attract voters from the centre-right, a far larger pool of an untapped electorate for the PQ that currently supports either the Liberals or the CAQ.
The pro-business credentials he brings to the PQ is especially problematic for the CAQ, which has already been squeezed on the charter debate.
But the most important thing about Péladeau's candidacy is the signal it sends. For a man of his wealth and influence to throw his hat into the political ring is no small thing, particularly since he will have to play second fiddle to Marois.
He may have designs on the top job at some point, but the move is a tremendous vote of confidence in the PQ. It is impossible to imagine Péladeau or someone of his stature running in 2012, when support for the PQ was soft and doubts still existed about Marois’ leadership.
The effect Péladeau will have on the campaign has yet to be recorded, but undoubtedly it will be significant. That the other party leaders spent the day reacting to the news demonstrated just how much it had set the agenda.
Act One goes to Marois and the PQ. Now on to Act Two.
Éric Grenier taps The Pulse of federal and regional politics for Huffington Post Canada readers every week. Grenier is the author of ThreeHundredEight.com, covering Canadian politics, polls and electoral projections. You can pre-order his eBook, "Tapping into the Pulse", a retrospective of polling in 2013, here.
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