OTTAWA - If it was a B movie, it might be billed as the Tyrant versus the Three-Headed Monster.

Prime Minister Stephen Harper's minority Conservative government is poised for defeat at the hands of the three opposition parties Friday in the House of Commons, raising the curtain on at least five weeks of political theatre and a federal election in early May.

The rhetorical trailers are already being aired.

The Tories are reprising the evil coalition theme they exploited so successfully following the 2008 election, when Harper prorogued Parliament rather than allow his freshly minted minority to be defeated by a Liberal-NDP coalition backed by the Bloc Quebecois.

Liberals, New Democrats and Bloquistes are painting Harper as an undemocratic tyrant -- and a hypocrite, to boot -- and will highlight their point Friday with a non-confidence motion based on unprecedented contempt-of-Parliament charges.

The prime minister is expected to formally dissolve Canada's 40th Parliament with a trip to the Governor General on Saturday morning, making Election Day either May 2 or May 9.

For all intents and purposes, the campaign is already well underway.

Conservative cabinet ministers and backbenchers managed to squeeze 18 "coalition" references into Thursday's 45-minute question period in the Commons. And the party has rolled out a new ad that ominously frames Liberal Leader Michael Ignatieff between Jack Layton of the NDP the Bloc's Gilles Duceppe.

"The real scandal here is that the Liberal-led coalition with the NDP and the Bloc Quebecois won't even accept the democratic will of Canadians," Conservative House leader John Baird thundered at one point.

Ralph Goodale, his Liberal counterpart, shot back: "Nobody will take lessons on democracy from this crowd!"

A Liberal-sponsored motion to be voted on Friday reads in part that: "the government is in contempt of Parliament, which is unprecedented in Canadian parliamentary history, and consequently, the House has lost confidence in the government."

A series of ethical stone chips, parliamentary stonewalling and overly partisan gambits have marked Harper's big blue machine in recent weeks and the Liberals hope to make trust the central issue of the campaign.

In that theme, the Liberals sent on open letter Thursday to the clerk of the Privy Council, the most powerful bureaucrat serving the prime minister.

"On behalf of Canadian taxpayers concerned about further abuse of public funds, we are calling on you to ensure that all government of Canada advertising stops immediately once a vote of non-confidence passes in the House of Commons," stated the letter.

The government has flooded the airwaves with $26 million worth of feel-good Economic Action Plan ads over the past 11 weeks and bureaucrats were directed late last year to start using the "Harper Government" in place of Government of Canada on departmental news releases.

Liberals have taken to calling the government the "Harper regime," an unsubtle analogy to events in the Arab world.

Conservatives hint darkly at economic Armageddon if Canadians are forced to cast a ballot at such a delicate moment -- even though Harper called an election just as the country was headed into recession in 2008.

It promises to be an election heavily freighted with over-the-top denunciations. In the memorable phrase of political scientist and former Harper adviser Tom Flanagan: "It doesn't have to be true. It just has to be plausible."

Layton dismissed the coalition talk as Republican-style fearmongering.

"Try to make people frightened and angry," he said. "This is the style that the Conservatives are accustomed to, directly imported from United States politics. This is not Canadian leadership, that's for sure."

He made a point of reminding Canadians that Harper proposed defeating Paul Martin's minority Liberal government on its throne speech in 2004 and replacing it, with NDP and Bloc backing.

Duceppe revelled in the details Thursday, describing the Delta Hotel on Maissonneuve Boulevard in Montreal where Harper convened the conspirators.

"He was coming in my office saying, 'If Martin is going to lose confidence, what do you want in the throne speech? What would you like in the budget?"' said Duceppe.

Expect more of the same in coming weeks.

Layton plans to hold his kickoff rally in Edmonton on Saturday afternoon, where New Democrat Linda Duncan holds the only non-Conservative seat in the province. The NDP hopes to expand its toe-hold in the Edmonton area, while the Conservatives are itching to bring Edmonton-Strathcona back into the fold and restore Alberta's solid blue hue.

Ignatieff will open his campaign on Parliament Hill before heading to Montreal.

Duceppe, as usual, will campaign exclusively in Quebec.

Harper's plans remain a mystery.