The fate of the 40th Parliament is in Jack Layton's hands.
The Conservatives will pepper Tuesday's budget with spending on NDP priorities, such as home-retrofit incentives, help for seniors and more doctors for rural Canada - but it will be Mr. Layton and his 35 New Democratic Party MPs who will decide whether to declare victory or dismiss the Harper government's offerings as an insincere fig leaf.
Conservatives need Mr. Layton's support to stay in office. Liberals need the NDP's votes to bring down the Harper government this week.
It is a rare moment of major influence for the leader of the fourth party in the House of Commons, a man who is not only fighting prostate cancer but who also underwent hip surgery earlier this month.
True to the form that he steadfastly maintained in the two months running up to the budget, Mr. Layton refused to tip his hand Monday as to whether partial action on his pre-budget wish list would be enough for him to keep the government alive.
NDP officials privately say it would take a lot for the party to support the budget - in part because it effectively means supporting the government for many months as the various budget votes play out in Parliament.
The party decided that in the run up to this budget, playing coy has its benefits. The party's priorities received weeks of attention in the media, which could serve the party well whether or not there is an election.
The flip side is that the Liberals and Bloc Québécois staked out early and hard pre-budget positions, leaving the pressure on Mr. Layton's shoulders. Prime Minister Stephen Harper's only pre-budget meeting with an opposition leader was with Mr. Layton, underscoring the fact that the Conservatives saw the NDP as its next potential partner after relying on the Liberals for the past two budgets.
Tuesday's budget will force Mr. Layton to finally step down from the fence - and the Conservatives are not giving him an easy decision.
The Harper government's 2011 budget will act on some - but certainly not all - of the NDP's five proposals for action: help for low-income seniors; pension reform; home-heating rebates; alleviating doctor shortages; and home-energy retrofit incentives.
An orchestrated leak to The Globe and Mail and other media outlets Monday and earlier government statements mean some of the budget's contents are already known.
The budget will include a plan to boost health-care services in rural and remote areas by forgiving up to $40,000 of student loans for new doctors and $20,000 for nurses who provide health care in these regions.
There will also be $400-million to renew the EcoEnergy Retrofit program, which encourages home owners to make energy-saving renovations. And Finance Minister Jim Flaherty has long hinted that the budget will include measures to help low-income seniors.
While those three items are part of the NDP's wish list, the Conservatives have already ruled out immediate pension reform and cutting the HST on home heating. That leaves the NDP's 36 MPs in a bind. The party insists it will not vote for a "fig leaf" budget that offers only tepid action in these areas. At the same time, it is running ads with Mr. Layton that appear to set a low bar for supporting the budget. In one ad, Mr. Layton says that while not every problem can be fixed, leadership means taking "proactive first steps in the right direction."
Some of the items promised by the Conservatives could be particularly attractive to NDP MPs who represent rural ridings. The Conservatives repeatedly target rural New Democrats for refusing to side with the government's efforts last year to scrap the federal long-gun registry - a point the Conservatives brought up again Monday in the House of Commons.
NDP national director Brad Lavigne declined to say whether the government's pre-emptive disclosure of budget contents would secure New Democratic votes.
"We have to look at the budget as a whole," he said. "It is impossible to comment on a few lines of strategic leaks from the government."
In addition to Tuesday's budget, the government faces an imminent vote that it is in contempt of Parliament, as well as confidence votes this week on government spending and political fallout over potentially illegal lobbying by Bruce Carson - a former senior aide to Mr. Harper - that has forced the government to call in the RCMP.
The Liberals and Bloc worked hard in Question Period on Monday to make this latest Conservative scandal stick.
It's the most recent ethics controversy tied to current or former Tory staffers, including charges laid against Conservatives for willfully exceeding election spending limits in the 2006 vote.
In contrast, the NDP Leader chose to ask questions about the situations in Japan and Libya - though Timmins-James Bay NDP MP Charlie Angus later launched a fiery attack over the Carson case.
Budget coverage: At your computer or on the go
Newsletter: Get the news delivered to your inbox with our special budget edition of our politics newsletter
Follow us on Twitter:,