TORONTO — Liberal Leader Dalton McGuinty signed a promise not to raise Ontario taxes Thursday in a bid to wrest the mantle of fiscal responsibility away from the governing Conservatives.

Surrounded by some of his most prominent caucus members, McGuinty signed a pledge from the Ontario chapter of the Canadian Taxpayers Federation committing his party to abide by a Tory taxpayer protection law passed amid great fanfare in 1999 under the watchful eye of former premier and self-proclaimed tax-cut champion Mike Harris.

"I, Dalton McGuinty ...promise that if my party is elected as the next government, I will not raise taxes or implement any new taxes without the explicit consent of Ontario voters," he said.

"I promise to abide by the Taxpayer Protection and Balanced Budget Act."

Under the stewardship of former finance minister Ernie Eves, the Conservatives have relinquished the right to call themselves prudent fiscal managers, McGuinty said.

The Tories plan to give away taxpayer dollars "by the billions" to big corporations and private schools, a tactic that will mean a larger deficit and more spending cuts, he said.

"(Eves) is making reckless and irresponsible promises totalling $10.3 billion," he said.

"We've had a financial plan out there for months; people know exactly what we're going to do, exactly how much we're going to spend, and where we're going to get the money."

The whole event made for a remarkable spectacle considering how long the Conservatives have worn the crown of fiscal responsibility in Ontario _ an era that McGuinty made clear Thursday is at an end.

If the Liberals pull it off, it would represent a major coup for the party that polling data suggests is in a neck-and-neck race with the governing Tories.

"I represent a new generation of Liberals in Ontario," McGuinty said.

The Conservatives have criticized the Liberals for promising to roll back tax cuts already implemented by the governing party, a tactic they say amounts to a tax hike, plain and simple.

An impromptu appearance Thursday by former finance minister Jim Flaherty certainly made it appear as though the Liberal attempt to steal the Tories' thunder had hit the Conservatives where they live.

Not so, said Flaherty, insisting that the Tories have the track record to prove they're the more fiscally responsible party.

"They're going to repeal tax reductions in Ontario, thereby increasing taxes by $4.6 billion, while at the same time they're signing a taxpayer protection act," Flaherty said.

"He's going to have to decide which promise he's going to break."

The terrorist attacks of Sept. 11 forced the Conservatives themselves to do an end-run around their own taxpayer protection laws, but that "all worked out in the end," Flaherty said.

John Williamson, the Ontario president of the Canadian Taxpayers Federation, said the Oct. 2 election would be considered a referendum on tax increases as is called for in the act.

Flaherty "respectfully disagreed," leaving Liberal finance critic Gerry Phillips incredulous.

The act -- drafted with the help of Flaherty -- makes it clear that an election is indeed a suitable referendum on tax cuts, Phillips said.

"To hear Mr. Flaherty today say that's not a clear referendum is panic at its worst ...this is quite extraordinary."