One of Quebec's most temperamental businessmen has stepped forward to run as a candidate with the Parti Québécois.

Media magnate Pierre Karl Péladeau stepped down last year as president and CEO of Quebecor Inc.

He's now on the ballot as the PQ standard bearer in Saint-Jérôme.

It's unprecedented for a media proprietor of Péladeau's influence to seek elected office at the provincial or federal level in Canada.

In 2012, Pierre Karl and his brother Erik Péladeau ranked 97th on Canadian Business magazine's list of 100 richest Canadians, with a net worth of $673 million.

The Péladeau family, initially led by their deceased father Pierre, created Quebecor, whose holdings include the right-wing Sun newspaper chain, the right-wing Sun News Network (sometimes called Fox News North), and the 24 hours papers.

Business journalist Gordon Pitts wrote about Pierre Karl Péladeau's volatility in the 2002 book Kings of Convergence: The Fight for Control of Canada's Media: 

He is emotionally turbulent, moving from calm analysis to childish delight to torrential profanity in the span of a minute. It would be too facile to dismiss this as simply Gallic emotion. No one does Gallic quite like Pierre Karl. And yet despite this erratic personality, he manages to come out of it appearing charming and roguishly likeable—and ultimately very smart.

Pitts described Péladeau's father as "a shameless womanizer, separatist sympathizer, alleged anti-Semite, reformed alcoholic and manic-depressive". On the positive side, he was characterized as "an intellectual, a student of philosophy and a classical music buff whose hero was Beethoven".

"Pierre Karl's early manhood was spent in open rebellion against his father, as he zealously espoused left-wing causes," Pitts reported. "He took up the spelling of his second name—it was originally Pierre Carl—because of his admiration for Karl Marx. He studied philosophy at the Université du Quebec à Montréal, where he developed a taste for communism, even distributing leaflets for the party."

By the age of 22, Péladeau began studying law and, according to Pitts's book, later "threw himself into the family business, now a committed convert to capitalism".

Péladeau held a news conference in Vancouver in 2005 announcing the launch of 24 hours in partnership with Vancouver businessman Jim Pattison. Pattison subsequently sold his stake in the commuter paper.

Meanwhile, Quebecor announced today that Péladeau has resigned as vice chairman and director of Quebecor, as well as quitting as chairman and member of the boards of Quebecor Media and TVA Group.

If he's elected to the Quebec National Assembly, Péladeau has pledged to put his Quebecor holdings in a "blind trust" or "under a blind management agreement". 

"Quebecor management wishes to stress that the newsrooms of its media properties will continue to operate fully independently and to defend the public interest," the company claimed. "Coverage of the current Québec provincial election campaign will continue to be fair and impartial towards all political parties and candidates."

Péladeau was mentored as a young business executive by former prime minister Brian Mulroney.

Mulroney, vice chair of Quebecor, and chairperson Françoise Bertrand issued this statement: "Quebecor employs 12,000 people in Québec and nearly 16,000 across Canada. As one of the Canada's largest private employers, our priority is to create shareholder value."

Quebec voters go to the polls on April 7.