Liberal Leader Stéphane Dion listens as Prime Minister Stephen Harper responds to during question period in the House of Commons on Parliament Hill in Ottawa. (Chris Wattie/Canadian Press)Prime Minister Stephen Harper accused Liberal Leader Stéphane Dion of betraying Canadian voters with the proposed Liberal-NDP coalition to replace the Conservative minority government, saying Dion is "turning his back" on the results of the recent federal election.

Harper, whose government currently faces almost certain defeat in a confidence vote, also told the House of Commons during Tuesday's fiery question period that Dion was about to make the "worst mistake the Liberal party has ever made in its history" by agreeing to support from the sovereigntist Bloc Québécois.

"Not a single member of this House, not even a member of the Bloc, received a mandate to have a government in which the separatists would be part of the coalition," Harper said.

"Mr. Speaker, if the leader of the Opposition thinks he has support for this, he should have the confidence to take this to the people of Canada, who will reject it."

In response, Dion accused Harper of hypocrisy in his efforts to keep his government from falling in a confidence vote.

The Liberal leader quoted a 2005 letter Harper wrote as Opposition leader that called Paul Martin government's avoidance of confidence motions a "violation of the fundamental constitutional principles of our democracy."

"Mr. Speaker, every member in this House has received a mandate from the Canadian people to deliver a government that will face the economic crisis," Dion said.

"The prime minister failed. The prime minister doesn’t have the support of this House."

'I gave my word that I would support this country': Dion

Dion also said that while he was fighting for Canada as intergovernmental affairs minister in the Chrétien government, Harper was urging the building of firewalls "around the provinces we all love.

"Mr. Speaker, I gave my word that I would support this country," Dion said. "The Bloc Québécois guaranteed 18 months of stability, and that is what Canadians are getting from this coalition in this agreement."

The heated debate comes as Gov. Gen. Michaëlle Jean was returning home early from a state visit to Europe to deal with the upheaval on Parliament Hill, where she could decide the fate of the government in the next week.

Parliament is set to vote on a Liberal no-confidence motion on Dec. 8. If Harper's government loses, Dion would ask Jean to approve the proposed coalition government.

Harper could still delay the vote or prorogue Parliament until his government presents a budget in January.

NDP Leader Jack Layton, Bloc Leader Gilles Duceppe and Liberal Leader Stéphane Dion, left to right, in front of Canadian, provincial and territorial flags after a coalition signing ceremony in Ottawa on Monday. (Adrian Wyld/Canadian Press)During question period, Harper also accused Dion, NDP Leader Jack Layton and Bloc Leader Gilles Duceppe of deliberately avoiding being photographed in front of a Canadian flag during Monday's signing ceremony of the agreement between the parties.

"Mr. Speaker, they had to be photographed without it because … a member of their coalition does not even believe in this country," he said.

Video and photographs of the event, however, clearly showed at least two Canadian flags behind the three leaders, as well as a painting of the Fathers of Confederation.

Layton, in turn, told the House that Harper's tone toward the Bloc has changed since he proposed in a letter to the Governor General in 2004 that the Conservatives should be afforded an opportunity to form a government with the Bloc and the NDP if the Martin government were to be defeated.

"I didn't hear any of this high and mighty language and moral indignation from the prime minister when he signed a document along with myself and Mr. Duceppe a few years ago," the New Democrat leader said.

"He simply can't be trusted."

Speaking to reporters outside the Commons, the Bloc leader said the 2004 letter shows Harper "certainly wasn't as afraid as he is now of the naughty separatists."

Economic update sparked coalition talks

Talk of a coalition government was triggered when Finance Minister Jim Flaherty delivered his controversial fiscal update last Thursday.

Opposition parties blasted the Tories for failing to include a stimulus package for the slumping economy and accused the party of using tumultuous times to try to push through ideologically driven measures they said attacked women and public servants.

The Conservatives have since promised to present their budget on Jan. 27, with the suggestion it will contain a stimulus package, and have eliminated some of the most contentious issues from the fiscal update.

The coalition has vowed to make a stimulus package a priority, proposing a multi-billion dollar plan that includes help for the auto and forestry sectors.

Under the coalition accord, Dion would serve as prime minister until a new Liberal leader is chosen in May.

The coalition would have a 24-member cabinet with six New Democrats and 18 Liberals, and would operate with the support of the Bloc Québécois for at least 18 months.

With 77 Liberal MPs and 37 New Democrats, plus the support of 49 Bloc members, the three parties have more seats than the 143 held by the Tories.