TORONTO - The New Democrats dispute the Liberal government's math and say their budget proposals would not increase spending just as the province tries to eliminate a $15.2-billion deficit.

The Liberals need NDP support to pass the budget and avoid another election, but Premier Dalton McGuinty says the NDP's budget demands would add $1 billion a year in spending.

NDP Leader Andrea Horwath says her call for a new income tax on people earning more than $500,000 would pay for most of the NDP's budget demands.

Horwath says she was taken aback by McGuinty's claim about the cost of her party's demands, which she calls silly, and warns the Liberals are in for some tough negotiations.

The first vote on the budget motion is still two weeks away, and McGuinty says there's lots of time to reach a deal with the NDP and avoid defeating the minority government.

McGuinty says he wants to know specifically what programs the NDP would cut to pay for their demands, but Horwath says she's already presented all her ideas.