MP Ken Dryden joined fellowLiberal leadership contender Gerard Kennedy inopposing the parliamentary motion stating the QuÃ©bÃ©cois form a nation.
"This is pure politics," Dryden said. "All this started with the ludicrous concept of having a debate fundamental to the country based on different understanding of the word nation."
The motion passed Monday night in Parliament by a 266-16 margin.
Dryden, who is not considered one of the four leading candidates, has previously argued against his own party's proposed motionon recognizing Quebec as a nation. That motion is expected to be debated atthe Liberal convention this week.
Earlier, Kennedy confirmed that heopposed Prime Minister Stephen Harper's surprise motion recognizing the QuÃ©bÃ©cois as a nation within a unitedCanada.
"I'm here today to say I can't support the Harper-Duceppe motion because I don't think it's good for Canada," he said, crediting theidea jointly to the prime minister and Bloc QuÃ©bÃ©cois Leader Gilles Duceppe.
"I think it's a motion that is politically inspired, treating this country like a political trinket, and we need and should expect better."
The former Ontario education ministersaid the motion will cause problems because itis ambiguous.
"It doesn't sayâ¦ what a nation is for Quebec. It doesn't say what we mean by that, and if there was ever a time for un dialogue honnÃªte —for an honest dialogue with Quebec and the rest of Canadians —it's now.
"We should not be trafficking in symbols for which we don't know what they mean or we intend people to be misled by them."
Kennedy and Dryden'sstand could lead to a divisive debate on the weekend at the Liberal convention in Montreal, even though the motion passed easily in the Commons with support from Conservatives, New Democrats, most Liberal MPs and even the Bloc QuÃ©bÃ©cois.
Kennedy did not ask any of his supporters in the federal Liberal caucus to change their vote.
Rivals support the motion
Other mainleadership rivals supported the motion, but with varying degrees of enthusiasm.
Michael Ignatieff, thefront-runner, had embraced the idea of a Quebec nation within Canada even before the motion was introduced. Bob Rae and StÃ©phane Dion are on record as supporting the motion butsay they do notconsider it a priority.
Harper introducedthesurprise motion on Nov. 22, raising the ante on a Blocmotion that sought to declare Quebec a nation without reference to Canada.
The Tory government's motion states: "That this House recognize that the QuÃ©bÃ©cois form a nation within a united Canada."
The prime ministerhas said he is using the word nation in a "cultural-sociological" rather than a legal sense.