Ontario’s Liberal government is not ruling out adding to its budget an NDP proposal to raise taxes for Ontario's wealthiest residents.  

The tax hike on Ontarians who earn more than $500,000 a year is NDP Leader Andrea Horwath’s key demand for supporting the budget and avoiding another election.

"Those at the very top can pay a little bit more so everyday families can catch a break," she said.

The Progressive Conservatives have said they will vote against the budget, leaving the NDP holding more power since the mid-1990s. If the budget motion fails, Ontario’s minority government will fall, triggering an election call less than seven months after the October election.

Liberal Premier Dalton McGuinty promised not to raise taxes during last fall's election. But the NDP’s proposal could allow him to argue that instead of raising taxes, this move simply shifts tax to Ontario’s highest earners.

"We're going to try to see if there's a way we can come to some understanding without compromising the principles that inform the budget," he said. "What I can say about the NDP is at least they are making a sincere effort."      

The Liberals currently hold 53 seats in the legislature, while the Tories hold 37 and the New Democrats the remaining 17.

The vote on the budget must take place by April 24.