WELLAND, Ont. - Prime Minister Stephen Harper says he won't hike taxes or cut spending to deal with the country's ballooning debt.

But critics say he can't be trusted to keep his word, and the NDP says he's already broken it.

Harper told a news conference in Welland, Ont., on Friday that the Conservative government remains on track to balance the federal budget by 2016 by controlling spending.

"Our spending for this recession, our stimulus spending, is temporary. It will end when the recession ends and we will return gradually to budget as our revenue recovers from the recession. So absolutely we do not require tax increases," Harper said.

"We do require spending discipline over the long term. We have to make sure that when the recession ends we end the temporary spending and other spending grows at a modest rate."

But the opposition questions both Harper's math and sincerity. They note that just a year ago, as the country was spiralling into recession, Harper said he would not run a deficit at all.

The government now expects a massive $56-billion shortfall this fiscal year alone, with multibillion-dollar deficits continuing until 2015-16.

The NDP said Harper is already raising taxes through the back door with planned increases to EI premiums and the introduction of the HST -- both of which will give Ottawa billions of extra dollars.

Many experts say there are only two options to eliminate the deficit: raise taxes or cut spending. But Harper and Finance Minister Jim Flaherty insist they can do it by limiting spending increases as the economy grows.

Economist Dale Orr released a report Friday calling the government's plan "unrealistic."

He said the Conservatives simply can't responsibly meet their 2015-16 target without raising taxes.

Orr proposes temporarily restoring the GST -- which the Tories cut by two percentage points -- to seven per cent until the budget is balanced again.

Parliament's independent budget officer, Kevin Page, has also suggested the government estimates are far too rosy.

But Harper defended the estimates.

"First of all, the scenario the government put out last month was the average of private-sector forecasters. Mr. Page may be more pessimistic than most. Our forecasts are actually right along the middle and that is absolutely our plan."

Harper also took a poke at Liberal Leader Michael Ignatieff, who once mused that tax hikes may be necessary to fight the deficit.

"Obviously the opposition has other plans," Harper said. "They want to make our stimulus programs permanent, they want to create a lot of other programs and, for them, they'll have to increase taxes. But, for us, it's something that we will not consider."