Michael Ignatieff's Liberals will try to push through a vote declaring the Harper government in contempt of Parliament Wednesday, a move that could set the stage for an election call in the days that follow.
Federal party leaders have been working furiously to prepare for a possible campaign as they head into an extraordinary week in Canadian politics. Much depends on the Conservatives' federal budget Tuesday and whether Stephen Harper's minority government can gain the support of one rival party to survive confidence votes on the economic plan.
No one is taking any chances, though.
The Liberals have secured a plane, wrapped their campaign buses with signs and launched an attack ad. New Democratic Party volunteers are starting to arrive at election headquarters in Ottawa and NDP election-style billboards have been erected in Montreal.
All opposition parties have agreed they want to vote the Conservatives in contempt of Parliament for stonewalling on requests for a more detailed costing of their tough-on-crime agenda.
Such a verdict would be unprecedented in Canadian history and could potentially hurt the Tories but it wouldn't automatically defeat the government because it's not a confidence motion. If the Conservatives are found in contempt, though, it would put the onus on Mr. Harper to test whether he still has the confidence of the House.
While Mr. Harper can use parliamentary procedure to try to delay a contempt vote that could come late Wednesday, he still faces a political minefield in the Commons.
But there are so many confidence votes on the parliamentary calendar that it's only a matter of time before the three opposition parties agree to defeat the Tories - and trigger an election - or one decides to back the Conservatives and stave off a late spring ballot.
All opposition parties are playing things close to their chest right now, making it difficult to discern how united they are in their intention to fight an early spring election.
While the Harper government is promising to focus on restraint and offer little in new funding or programs, the March 22 budget could contain surprises, which would make it palatable to at least one opposition party.
NDP Leader Jack Layton could end up determining whether Canadians head to a spring election because his party is the only one that appears to have left open the possibility of backing the Tory budget.
The Liberals have demanded the Tory fiscal plan roll back corporate tax cut promises, a request the Conservatives have rejected out of hand. The Bloc Québécois had demanded cash for a sports arena - turned down by the Conservatives - and a deal to compensate Quebec for adopting a harmonized sales tax. Talks on the HST deal are continuing but the Tories have suggested an agreement would not be ready for the Tuesday budget.
Should neither the NDP nor the Bloc agree to back the budget, there are several money bill votes this week that constitute confidence votes and could provide windows of opportunity to defeat the government.
If Mr. Layton and Bloc Leader Gilles Duceppe fail to back the fiscal plan, Liberal insiders say this would make them determined to proceed with a no-confidence motion on Friday in the Commons.
The NDP has laid out a list of demands for the budget, including increased support for low-income seniors, expanded Canada Pension Plan coverage, a tax rebate on home heating fuel and the hiring of new doctors.
But it's staying mum on precisely how much in terms of measures would earn its support.
"We don't vote for the government without something substantial in return," said Brad Lavigne, party national director.
The NDP says Mr. Layton's health will not deter him from an election. He has been battling prostate cancer and recently underwent hip surgery. "His doctors have given him the green light to run a campaign if need be," Mr. Lavigne said.
On the contempt motion, a Commons committee is expected to table a report with Parliament Monday saying the government's failure to produce sufficient data on its tough-on-crime bills "constitutes contempt of Parliament."
Forty-eight hours after this point, by Wednesday afternoon or evening, the Liberals could seek a vote asking whether the Commons "concurs" with the report.
Opposition parties expect the Conservatives may try to delay this contempt vote but they are hoping Commons Speaker Peter Milliken makes it a priority Wednesday because it's a question of parliamentary privilege.