ACTON VALE, Que. - Pierre Trudeau has made a sudden reappearance in a Canadian federal election -- a decade after his death.

Prime Minister Stephen Harper is warning that if his rivals get elected, the country will return to the days of economic darkness when it was led by his late Liberal predecessor.

The early 1970s -- a time when a minority Liberal government relied on support from the NDP -- inflicted long-term damage on the Canadian economy, Harper said Sunday. It led to two decades of runaway spending, higher taxes, double-digit unemployment and interest rates, he added.

"All they did was spend money," the prime minister said from a farm in Acton Vale, Que.

"We were a generation fixing those problems. When I look at the Liberal platform today ... I'm saying that's the alternative. That is the route the country will go down unless it stays on the path we're on, with a strong, stable majority Conservative government."

Harper may have been pleased to talk about his opponents' platforms, but he was a little more vague when asked a key question about his own plan: Where would he find the $4 billion in annual budget cuts he's promising?

Harper says it should be easy to find those so-called inefficiencies to help slay the deficit -- but is offering few clues about where he'll cut.

His opponents, however, warn that cuts announced in the Tory platform could mean serious damage to social programs, like health care.

The NDP is promising to balance the books within four years in its platform, which was released Sunday. The party is making the cornerstone pledge while at the same time committing itself to billions of dollars in new social spending.

The NDP is also ripping a page out of Harper's 2006 campaign playbook and promising five key priorities to be accomplished in the first 100 days of taking office.

The Tories used a similar strategy -- relying on a set of focused, easy-to-understand policies -- to defeat Paul Martin's Liberals.

The NDP platform -- the last one released by a major party -- is a mix of previous New Democrat commitments from earlier campaigns and initiatives the party has already put before the House of Commons in proposed legislation.

The five key priorities include hiring more doctors right away, strengthening public pensions, cutting small business taxes, capping credit-card rates at prime plus five per cent, and bringing in new accountability legislation. Specifically, the NDP says it wants to limit the power of the prime minister to prorogue Parliament.

It pledges to balance the federal books by 2014-15 and, while there is significant spending right away, senior campaign officials say it would not add to the deficit.

The centrepiece of the NDP's fiscal plan is to restore the corporate tax rate to 19 per cent and to crack down on foreign tax havens. The NDP are also pledging to cut small business taxes by $1 billion.

There's a promise to compensate Quebec for harmonizing its sales tax and another promise to pull out of the Afghan training mission.

NDP Leader Jack Layton says neither of the two bigger parties -- the Conservatives or Liberals -- can be trusted to look out for families.

"It's two sides of the same coin. But they're still taking your money and they're not making sure that your family gets what it needs when it's facing real challenges," Layton said. "And that's why we've put together these commitments."

The key planks of the Liberal platform revolve around education -- including more money for students to attend university and for parents to afford day care.

The Liberal plan would be funded partly with a hike in corporate tax rates to last year's rates. Some analysts warn, however, that there's a fiscal hole of several billion dollars in their plan.

The Tories are accused of hiding an even bigger hole in their platform -- by treating $4 billion in spending cuts like they've already happened and by announcing an increase in health spending without accounting for it.

The Tory platform promises to erase the deficit a year earlier than planned, while providing considerable tax breaks to couples with children through a mechanism that would allow them to pool parts of their incomes. That promise, however, would only kick in if and when the federal budget is balanced, in several years.

When asked for his thoughts on Trudeau, personally, Harper was reluctant to mention him by name.

"I think it's probably a bit unfair to bash somebody in the grave," Harper said.

"He's not here to defend himself. But as you know, Mr. Trudeau did have a different philosophy of government -- a high-spending philosophy, centralizing philosophy -- and that's not the philosophy of this government."