TORONTO -- NDP Leader Tom Mulcair is backing away from his pledge to restore up to $36 billion in provincial health care transfers as he vows to pay for other pricey campaign commitments within a balanced budget.

Mulcair insisted Thursday that an NDP government would make it a "top priority" to honour his health funding commitment, but acknowledged it's not likely to happen right away.

The NDP leader first made the promise last summer in what his party called a "historic" speech to the Canadian Medical Association. He castigated Stephen Harper's government for its plan to reduce the rate of increase in health transfers to the provinces starting in 2017, a move he said would rob the provinces of up to $36 billion over 10 years.

"An NDP government would use any budget surplus to cancel the proposed cuts to health care," he said at the time.

However, since then Mulcair has said little about that promise while he's added a number of others -- including a $5-billion national child care program -- that would apparently take priority.

Pressed on the health transfer issue Thursday during a campaign stop in Toronto, Mulcair said it now appears the budget surpluses on which he based his promise won't materialize.

Still, he said there are two years before the scheduled reduction in transfers start so there's still time.

"We had said that any surplus, because Mr. Harper had been promising surpluses, would be dedicated in our case first and foremost to avoiding that (transfer reduction)," Mulcair said at the campaign office of his star candidate Andrew Thomson, a former Saskatchewan finance minister.

"Now it looks pretty obvious that there won't be any, but during that two-year period our health minister will have as a top priority to get new health accords."

He added that the NDP's health care priorities will include home care and pharmacare.

Conservative spokesman Stephen Lecce said their government "significantly increased" health spending.

"Under prime minister Harper, our government is delivering the highest health transfers in Canadian history -- reaching $40B annually by the end of the decade," he said in a statement.

Based on Bank of Canada projections, the parliamentary budget office has said the federal government is likely headed for a $1-billion shortfall in 2015-16, despite a projected surplus in the 2015 budget.

Nevertheless, Mulcair has been adamant this week that his first budget next year would be balanced and he's said he believes subsequent budgets would be balanced too. He has not addressed how or if he would find a surplus to funnel into health transfers while honouring all his other campaign commitments.

The Liberals have said they're skeptical Mulcair could balance his budget without spending cuts, but Mulcair has said he is "not entertaining any thought" of a deficit. He has not talked about spending cuts.

Mulcair's big-ticket promise to create one million $15-a-day child-care spaces would cost $5 billion annually once fully implemented in eight years. He has proposed several new tax credits and lowering the small business tax rate.

He said Thursday he'll pay for NDP promises by eliminating Harper's $2-billion income-splitting plan, wasteful government advertising, the Senate, subsidies to oil companies and court battles with First Nations.

The Liberals were quick to point out that several provinces oppose Senate abolition, calling the idea he could achieve savings by budget time "laughable."

Mulcair has also said he would raise the 15-per-cent corporate tax rate, but has not yet specified by how much.

He has not yet released the full costing details of his platform.

Asked Thursday if he would use carbon pricing to help balance the budget, Mulcair was noncommittal.

"We've always talked about cap-and-trade as the best way of ensuring that there is a guaranteed reduction (in greenhouse gas emissions)," he said.

"There's more and more information from other possibilities. We're not going to take a one-size-fits-all approach. I will work with the provinces and territories, but the federal government is going to have to start showing leadership on this."

Mulcair said in 2013 that the NDP would create a cap-and-trade system, putting a "clear market price" on carbon. He's previously said that any revenue generated would not go into general federal coffers but would be poured back into environmental programs in the provinces that pay the carbon tab.