OTTAWA - Call it the cross-your-fingers deficit elimination plan.

Finance Minister Jim Flaherty's plan to largely get rid of the deficit in five years depends on a trifecta of happy news - uninterrupted economic growth, historically low interest rates and uncharacteristic spending restraint.

Even so, Flaherty still has yet to project a balanced budget - a notable omission for a Conservative government that has prided itself on sound economic management.

The plan outlined on Thursday still leaves a $1.8 billion deficit in the final year of the projection period - 2014-15 - by which time Ottawa will have added $158 billion to the national debt.

But as if channelling former Liberal finance minister Paul Martin's "come hell or high water" declaration of war on the deficit in the 1990s, Flaherty insisted the country will return to surplus, just beyond the budget's horizon - in 2015-16.

"If the economy did not grow as anticipated by the private sector economists, we could do more if we had to," he said. "But we are getting to balance, we are committed to returning to surpluses. This government will return to balanced budgets."

Analysts said the government numbers only work if the recovery continues apace with no surprises, keeping government revenues pouring in reliably from now until mid-decade.

As well, the budget is counting on Treasury Board President Stockwell Day to limit spending growth to 1.5 per cent in 2012-13 and 2.5 per cent in the subsequent two years - about the rate of projected inflation.

Making the task even harder, the budget will count on interest rates rising no more than two percentage points from the current historically low levels.

"There's not a lot of room for error," said Kevin Dancey, chief executive of the Canadian Institute of Chartered Accountants and a former Finance associate deputy minister of tax policy.

"In terms of the growth projections and interest rate projections, if they are off by even one per cent that's going to have a significant effect and there's no contingency in this."

As the numbers stand, Ottawa is pencilling in $17.6 billion in savings, from such things as the freeze in department operating budgets and MP and senators' salaries, restraining growth in defence spending, and a freeze in international assistance after this year. As well, savings from ongoing strategic reviews will be mostly pocketed rather than re-allocated.

Although there are few details, analysts say the spending restraint will mean that the public service will get smaller, and Canadians will have to do without any significant new goodies from Ottawa for five years.

NDP critic Thomas Mulcair said the lack of details of how Ottawa will rein in spending in the bureaucracy should worry Canadians as much as the bureaucrats.

"We have no idea what the plan involves and that's a great source of concern because historically the first thing that gets cut is direct service to the population, not the bureaucracy that supports it," he said.

Flaherty is counting on economic growth to do the rest to balance the budget. Many doubt it will be so easy.

Parliamentary budget watchdog Kevin Page recently projected the deficit would still be above $19 billion in 2013-14, about $11 billion more than Flaherty is predicting. In Page's analysis, the government won't cut spending as much as it says it can, nor will corporate revenues meet expectations, and debt-servicing charges will be higher.

"The short answer is that it is doable," said Bank of Montreal economist Douglas Porter. "But it will require an extended period of real discipline and that's something we haven't seen from federal governments of any political stripe in the last 10 years."

In fact, the Harper Conservatives have increased spending by about seven per cent a year since their election in 2006.

The real test, said Porter, is what happens next year when the government withdraws the $19 billion of stimulus that constitutes the second portion of its economic rescue package introduced last year. The shock to the economic system may be enough to throw Ottawa's economic growth projections off whack, he said.

Flaherty conceded that the further out the projections go, the more uncertain they become.

But he also noted Monday's news that the economy grew by five per cent in the fourth quarter of last year, and nominal growth - where Ottawa derives its revenue - was above nine per cent. That gives some hope there is as much upside risk to the projections as downside, he said.

But ironically, the more the government looks like it may meet its target, the more difficult it may get, cautioned Scotiabank economist Derek Holt.

With most advanced economies expected to continue carrying crippling debt burdens, Canada's superior fiscal position may give an unwelcome boost to the Canadian dollar, thereby further damaging the key export sector of the economy that gains from a low-flying loonie.

"It's going to give more of an overweight Canada story that's going to lead to a further appreciation of the Canadian dollar and bringing downside risk to growth that might shortcut their ambitious projections," he explained.