NDP Leader Jack Layton, left, shakes hands with Liberal Leader Stéphane Dion, centre, and Bloc Québécois Leader Gilles Duceppe on Monday after signing a coalition agreement on Parliament Hill. (Adrian Wyld/Canadian Press)

The Tory government has signaled it is considering all legal options to prevent a Liberal-NDP coalition from taking power, and it has launched a public relations blitz to discredit the pact.

CBC's Keith Boag, who attended a briefing at the Prime Minister's Office, said it is likely the prime minister will ask Gov. Gen. Michaëlle Jean for the prorogation of Parliament, suspending the current session until the new year in hopes of subverting the coalition.

The opposition parties formally signed an agreement on Monday that would see Liberal Leader Stéphane Dion lead a coalition government with the NDP, supported by the Bloc Québécois, for at least 18 months.

That evening, Prime Minister Stephen Harper told Tories gathered behind closed doors for their annual Christmas party at an Ottawa hotel that the party will "use all legal means to resist this undemocratic seizure of power."

"My friends, such an illegitimate government would be a catastrophe, for our democracy, our unity and our economy, especially at a time of global instability," Harper said.

In an effort to rally public support against the deal, the Conservatives are expected to drive home the message that the agreement, is in fact, a three-party coalition, with the Liberals and NDP in bed with the separatists.

In Tuesday's question period, the onslaught began with Conservative MPs branding the partnership as the "separatist coalition."

Through radio and TV ads, the party will also point out that the Bloc Québécois will have a veto power over the coalition.

The text of the radio ads includes the message that voters should decide what kind of government arrangement they want.

One radio commercial concludes: "[Dion] even thinks he can take power without asking you, the voter. This is Canada. Power must be earned, not taken."

CBC's Boag said it appears the Conservatives have decided that the only viable solution is Canadians heading back to the polls.

Rival rallies planned

Supporters of the government told the Globe and Mail the public relations campaign may consist of petitions, advertising and rallies across the country, including at Rideau Hall, home of the Governor General, and on Parliament Hill.

Meanwhile, proponents of the proposed coalition also announced planned rallies across Canada to show support for the plan, using social networking websites such as Facebook to spread word of the events.

The Tories have also appealed to their supporters to write and to go on local radio stations to voice their concerns, CBC's Margo McDiarmid reported. The party has also set up a website where members can put in their postal code and find the contact numbers for their local radio stations and also find help in writing letters to the editor.

At the Conservative Christmas party, party members were seen sporting buttons that read "No to the coup."

Asked about how the opposition plans to counter the public relations war, NDP Leader Jack Layton responded, "Well, we're going to talk to Canadians and tell them the truth about what's happening here." He did not reveal any details.

Dion advises Gov. Gen. of intentions

Dion has said he has advised Jean in a letter that he has the confidence of the Commons to form the government should Stephen Harper's Conservatives be defeated in a confidence vote, planned for Dec. 8.

The opposition parties have said they made their move after Harper "did nothing" to address the current economic crisis. Their accord includes a proposed multibillion-dollar stimulus package with support for the auto and forestry sectors.

The proposed coalition cabinet would comprise 24 ministers and the prime minister. Six of these ministers would be appointed from within the NDP caucus. The position of finance minister would be held by a Liberal while the NDP would be allotted six parliamentary secretaries.

The accord between the NDP and Liberals would expire on June 30, 2011, unless it is renewed. The Bloc is only committed to 18 months.

Among Harper's options to thwart the pact is to prorogue Parliament, meaning the Conservative government could not be defeated in the current session of the House. Harper would need the approval of the Governor General to do that.

Parliament is normally dissolved after the legislative agenda is finished, not before it begins. The constitution stipulates Parliament only has to meet once a year.

Harper could also ask Jean, who is currently returning from a state visit to Europe, to dissolve parliament and call an election, a decision that would send Canadians to the polls for a second time in less than two months.

"I think a lot of political science students are going into their university classes today asking their professors: To become prime minister of this country don’t you have to win an election?" Heritage Minister James Moore said in an interview Tuesday with CBC News.

Moore said all three opposition leaders expressly stated during October's election campaign that they would not enter into a coalition.

"Imagine if [Dion] campaigned saying if I’m elected I’m going to get into bed with the Quebec separatists to form a coalition government. I think Canadians would be rightfully outraged."

Green Party Leader Elizabeth May said her party unanimously supports the coalition.

"[The Conservatives] have lost the confidence of the House. It's broken and it can't be fixed."

"We really need on the urgent basis of our national economy and the urgent issue of the climate crisis to see a government that’s prepared to take action. It clearly isn’t the Conservatives and now the Canadian public, the majority of whom did not vote for Mr. Harper, have a coalition that meets that need."

With files from the Canadian Press