Philippe Couillard said Monday that he'll oppose the legislation because he believes the Parti Quebecois' Bill 14 takes the wrong approach to language.
Couillard said the province has had enough coercive measures over the decades to require the use of French, and they've worked well.
"Now it's time to move from coercion, to encouragement," Couillard said.
He said the bill's provisions, which set stricter rules on using French in businesses and make it easier to impose a French-only status on municipalities, take exactly the wrong approach: "I'm not really sure we'll protect the French language that way."
The bill appears in serious trouble. The Liberals were already opposed before they got a new leader, and the Coalition party has also demanded that its key provisions be gutted. Both parties have enough votes to easily defeat any government measure.
Couillard held a news conference Monday on his first full day as the leader of Quebec's Opposition party. He said he received congratulatory phone calls Sunday from two federal politicians — the interim leader of the Liberal party, Bob Rae, and his heir apparent Justin Trudeau.
Couillard downplayed the extent of his ties to a more controversial federal appointee, Arthur Porter.
He and Porter were once appointed by Prime Minister Stephen Harper to the committee that monitors Canada's spy agency, and they also ran a consulting business together.
Porter, a former hospital administrator, now faces fraud charges in connection with a scandal-plagued contract to build a large hospital.
The Liberal leader's opponents have already begun trying to use Couillard's past ties against him. One says Couillard, who is returning to politics after a five-year absence, must seek a legislature seat immediately to answer questions about Porter.
Couillard has said his immediate priority is rebuilding the party — not running for a seat in the minority parliament.
"You can't be a coward and deny your friendships," he said, admitting that he knew Porter well.
"But, this being said, it's very unfair to draw any association between me and the awarding of the contract."
He said he could never even have exerted any influence, had he wanted to, in the awarding of the controversial McGill super-hospital contract that has resulted in charges against Porter and former executives at engineering giant SNC-Lavalin.
The Liberal party will continue to be led in the legislature by Jean-Marc Fournier, who had been the interim party leader since the Sept. 4 election.
Premier Pauline Marois urged her new opponent to step into the parliamentary ring a little quicker.
"I hope hope he will come in the national assembly," Marois told a Montreal news conference, after congratulating Couillard on his win.
"Because it is the place where you discuss, where you adopt the law, where you participate in the democracy."
As for Couillard's relationship with the now-controversial figure, Marois said it could be problematic: "Let's just say that, in my opinion, it's a pebble in his shoe."
She said she hoped she would get more support on language issues than from Couillard's predecessor — although that was before she'd heard his comments Monday.
As for another thorny issue, Couillard has been playing down the urgency of his stated wish to reopen the 1982 Constitution to get a deal Quebec might approve.
His very mention of the issue has already had the pro-independence Parti Quebecois seeking to pull him in deeper; it demanded that he start laying out what new conditions he'll seek for Quebec.
The last Liberal leader, Jean Charest, steered far and wide of any discussion about constitutional reform. Charest himself was a veteran of the constitutional battles when he was a Mulroney Tory cabinet minister in the 1980s and '90s, and he expressed no nostalgia for them.
Charest discreetly drove home that perspective over the weekend, when he told reporters at the Liberal convention that the No. 1 priority had to be the economy. When asked a follow-up question about the Constitution, Charest started to walk away from the media scrum.
At the same time, the PQ's minister responsible for "sovereigntist governance" was issuing a demand that Couillard start laying out constitutional conditions to get the discussion going.
Couillard downplayed the urgency of the issue Monday.
"We know the PQ's technique — which is to ask for a list as soon as possible," Couillard said.
He expressed a desire to see a new constitution, approved by Quebec, by 2017.
The endorsement of the 1982 Constitution by only nine provinces — all those except for Rene Levesque's Parti Quebecois government — became the defining issue of Canadian politics for the better part of a generation.
Attempts to reopen the agreement split the country into factions as Western Conservatives bolting to create the Reform party, the Bloc Quebecois was born, and support for Quebec independence skyrocketed.
The issue culminated in a 1995 sovereignty referendum that came within a percentage point of seeing Quebec leave Canada.
-With files by Alexandre Robillard and Pierre Saint-Arnaud
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