TORONTO - The honeymoon is officially over.

The so-called "happy marriage" of convenience between Ontario's minority Liberals and the New Democrats over the budget hit another rough patch Wednesday, with the Liberals accusing the NDP of breaking their wedding vows.

Finance Minister Dwight Duncan accused the NDP and the Progressive Conservatives of "using every stall tactic in the book" to block the budget, jeopardizing both Ontario's credit rating and a plan to slay the province's $15-billion deficit.

The NDP helped the Liberals survive a crucial budget vote a month ago after brokering a deal that included several of their demands, including hiking taxes on the wealthy.

The New Democrats say they only agreed to let the budget clear its first hurdle, by abstaining from a vote on the budget motion. But Duncan insists the NDP also agreed to allow the entire 357-page budget bill to pass.

"When is a deal not a deal?" Duncan asked. "I watch the media and I was privy to those discussions. That's what we agreed to."

The government made a billion dollars' worth of changes to garner the NDP's support "and what they're doing now is simply playing games," Duncan added.

The delay tactics include forcing 30-minute division bells to ring as often as possible, which has been holding up the budget debate for more than a month, he said.

But it's the Progressive Conservatives who are ringing the bells to protest the government's refusal to strike a special committee on Ornge, the province's troubled air ambulance service that's currently under a criminal probe.

With just eight sitting days left until the legislature rises, the government is prepared to extend debates until midnight and even over the summer to move the budget forward, Duncan said.

But New Democrats say they're not holding anything up and have made it clear to the government that they'll fast-track measures that they wanted in the budget.

"We negotiated with the government and our agreement was very clear," said NDP house leader Gilles Bisson. "We're not trying to squeeze them."

But there are elements in the huge budget bill that require public scrutiny, such as selling off government services like ServiceOntario that could lead to more Ornge-type scandals down the road, he said.

Bisson said his party won't support any motions to limit debate of the budget bill, but they are prepared to sit in the summer.

"I think there is a deal to be had there and it's not going to be excessive to the government," he said. "We're not going to get everything we want, they're not going to get everything they want, but we should be able get to this by the end of June."

The Liberals are acting like bullies, said Progressive Conservative finance critic Peter Shurman.

"The Liberals spent eight years with a significant majority and did whatever they pleased, and now they can't do whatever they please and they're acting like whiners," he said.

"I think the population of Ontario are sick and tired of hearing this constant whining about what we or the NDP are doing. I think it's time they looked into the mirror and decided that they have to change tactics."

Duncan warned that if the budget doesn't pass before the legislature breaks for the summer, key measures won't be implemented in time, including a corporate tax cut that's supposed to kick in July 1 and the NDP's surtax on the rich.

"The longer into this fiscal year you go, the more challenging implementation becomes," he said.

Duncan also raised the spectre of a possible downgrade by a second credit rating agency if the March budget is defeated and the province is plunged into another election.

"They want the parties of this minority legislature to work together, put in place a strong plan to balance the budget and hit the fiscal targets that we have laid out," he said.

Moody's Investors Service downgraded the province's debt rating on April 26, citing Ontario's growing debt burden and the need to stay on track to eliminate the deficit in 2017.

A few days before Moody's dropped its bombshell, Standard and Poor's also revised its outlook on the province's debt rating from "stable" to "negative."

Earlier on HuffPost:

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• What's In The Ontario Budget 2012

• Health Care

  The 2012 Ontario budget freezes pay for doctors, and extends a pay freeze for health care executives. The province will begin means-testing seniors' prescription drugs, paid for under the Ontario Drug Benefit Plan, effectively meaning that the 5 per cent wealthiest seniors covered by the plan will have to pay more into the plan. Seniors with incomes over $100,000 and senior couples with combined incomes above $160,000 will be affected. Increases in health care spending will be capped at 2.1 per cent per year.

• Education

  The budget freezes pay for teachers. A pay freeze for educational executives, already in place, will be extended. School boards in low-population areas will be amalgamated, and "under-utilized" schools will be shut. Student transportation will be cut by $34 million.

• Senior Citizens

  The province will begin means-testing seniors' prescription drugs, paid for under the Ontario Drug Benefit Plan, effectively meaning that the 5 per cent wealthiest seniors covered by the plan will have to pay more into the plan. Seniors with incomes over $100,000 and senior couples with combined incomes above $160,000 will be affected.

• Social Assistance

  Welfare rates will be frozen and planned increases to the Ontario Child Benefit will be delayed.

• Taxes

  There are no tax hikes in the 2012 Ontario budget, but it does freeze the corporate tax rate at 11.5 per cent, foregoing planned reductions in the tax rate to 10 per cent. The freeze is expected to save $1.5 billion over three years.

• Energy

  Ontario will cap the 10 per cent hydro bill rebate at 3,000 kilowatt-hours, a limit high enough that most homes won't be affected, but businesses could be. Reducing the tax credit will save $470 million over three years.

• Crime & Security

  On top of the four jails the province already plans to close, the budget adds two more to the closure list -- one in Brantford and one in Chatham. Overtime for jail guards and the Ontario Provincial Police will be reduced.

• Business Initiatives

  Ontario plans to reduce spending on business support programs by $250 million by merging a number of different programs.

• Gambling & Lotteries

  The province aims to increase revenue by increasing the number of gambling facilities. [Details to come]