McGuinty stepped back from his threats on Friday to go to the polls over changes the opposition parties made to the budget at committee Thursday. He also softened his tone after calling Horwath "disingenuous" for breaking earlier agreements not to block the budget's passage.
"The budget must remain intact," McGuinty wrote to Horwath Sunday.
"You need only ensure your caucus lives up to the agreements you have already made."
On Friday, McGuinty said he would call an election if the portions of the budget that were removed at committee by the NDP and Conservatives were not restored before Wednesday's final vote by the legislature.
But in Sunday's letter, McGuinty said those sections would be brought back in the fall as a separate bill. He urged Horwath to honour her promise not to block passage of the budget legislation.
"The budget bill must remain intact not only to fulfil our agreements, but more importantly, to provide the tools required to eliminate the deficit, grow the economy and create jobs," he wrote.
Horwath responded with a statement, saying she was always committed to seeing the budget pass to avoid another election.
"I am glad the premier has changed his tune of the last few days and is no longer making election threats," said Horwath.
"I am now more convinced than ever that we can avoid an election no one wants."
However Horwath still wasn't promising to pass the budget as is, and wants to deal with over 200 amendments at the finance committee on Monday and Tuesday.
"I have also committed to improve the (budget) bill at committee," she cautioned McGuinty.
"Now is a time to talk seriously about making minority government work and passing an improved budget that works for Ontario families."
Horwath also thanked both McGuinty and PC Leader Tim Hudak for responding to her appeal for weekend talks, but a Conservative spokeswoman said all the Opposition leader did was confirm the Tories will vote against the budget.
McGuinty complained the Liberals twice made deals with Horwath to ensure the budget passed, conceding to a tax on the rich and increased payments for people on welfare and social disability, and allowed extra committee hearings on the budget.
"On the basis of those two agreements, I believed _ and more importantly, Ontario families clearly understood _ the budget bill would pass," he wrote.
"But to my surprise and disappointment, your party began to dismantle the very budget bill you personally agreed to see pass."
The Liberal leader's more conciliatory tone Sunday was in stark contrast to Friday, when McGuinty's campaign chairman, Greg Sorbara, said he felt like Horwath had "stabbed" him in the back."
After failing to nail down details of the budget deals before, this time McGuinty told the NDP to put it in writing.
"Specifically, I ask you to commit yourself and your party, in writing, to not alter the intent or block passage of any more schedules of the budget bill," he wrote."
"And, of course, I will also need your written assurance that you will not block passage of the budget bill in the legislature."
The budget faces two more days of opposition-dominated finance committee hearings before the legislature is recalled Wednesday for the final vote, a confidence motion that could defeat the minority government and trigger an election.
McGuinty's letter Sunday made no mention the premier's threat Friday to call an election rather than have the opposition parties "gut" the budget to the point the Liberals felt it threatened deficit reduction targets and the economic recovery.
The Conservatives have vowed to vote against the budget since the day it was introduced, but surprised the government by teaming with the NDP to remove budget provisions to allow privatization of services.
The Liberals need only one New Democrat or Tory vote to pass the budget and avoid the defeat of the minority government, but the NDP could also abstain and allow the Liberals to out vote the Conservatives.
On Friday, McGuinty wouldn't say if he would prorogue the legislature for a couple of months to try and resolve the budget crisis rather than call a summer election.
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