Progressive Conservative Leader John Tory has lobbed a "grenade" into the education debate with his proposal to fund faith-based schools, Ontario Liberal Leader Dalton McGuinty said Monday.

Speaking at a Catholic high school in Markham, Ont., north of Toronto, McGuinty said Tory's plan is woefully lacking in detail.

"I think Mr. Tory is showing bad judgment. I think good judgment determines that we stand up for publicly funded education," the Liberal leader charged.

"It's not time to turn back and to plunge our kids and our publicly funded system of education into more disruption, more turmoil, more cuts and more conflict."

McGuinty says Tory's proposal threatens the public education system because it would take $500 million a year out of public education and segregate students.

It was the first time during the campaign that McGuinty has visited a Catholic school. He said his "responsibility for the public interest," not his Catholicism, is determining his position on the issue.

"I want to make publicly funded education so excellent, so irresistible, that all those kids that find themselves in our private schools today will say, 'I want to go to a public school,''' he said.

McGuinty was scheduled to speak to a gathering of Ontario principals later Monday in the nearby suburb of Richmond Hill.

In an interview early Monday on an Ottawa radio station, Tory said McGuinty was once in favour of funding religious schools if they followed certain conditions.

Tory says the Liberal leader is speaking out against the proposal now because he is a political opportunist.

Tory is spending Monday campaigning in eastern Ontario, with stops in Ottawa, Nepean and Cornwall.

Campaigning in the Toronto area, New Democrat Leader Howard Hampton said his rivals are using the debate on faith-based schools as a smokescreen for most important education issue.

Hampton says the focus should be on the broken funding formula and the fact that parents are being forced to raise hundreds of millions of dollars a year to supplement government funding.

"When I go from community to community, what people are most concerned about is their neighbourhood school, what people want to see is that their neighbourhood school is well-funded, properly funded," he said.

Hampton says the Conservatives don't want to talk about it because former premier Mike Harris was the one that created the funding formula mess, and he says Liberals want to ignore the debate because McGuinty has broken a promise to fix the situation.

The NDP leader is promising an immediate review of the funding formula, if elected, and a Local Priorities Grant to give school boards $200 per student to address local needs.

With a report from CTV's Paul Bliss and files from The Canadian Press