Greg Sorbara, McGuinty's longtime friend, confidant, campaign chair and former finance minister, announced he was resigning as the MPP for Vaughan to devote more time to his family, but would also stay on as co-chair of the Liberals' election campaign and head of their fundraising arm.
"Given the realities of minority government and the possibility of an election at any time the opposition parties chose to defeat the government, a great deal more needs to be done to prepare for an early election," said Sorbara.
"I feel it’s important to see to that mission, developing policies for that campaign, recruiting candidates for the ridings that we don’t hold, and raising the money necessary to...contest and win that election."
The Liberals hope to turn their minority government into a majority in two byelections this fall, McGuinty said as he stood beside Sorbara.
"I take heart in knowing that he’s still going to lead our effort in our campaign to secure a strong, stable majority," said McGuinty.
The premier has until October to call a byelection in Kitchener-Waterloo to replace veteran Progressive Conservative Elizabeth Witmer, who quit after the premier appointed her to a $188,000 post as chair of the Workplace Safety and Insurance Board in April.
Both the Kitchener-Waterloo byelection and the one in Vaughan to replace Sorbara will be held at the same time, and sometime after Labour Day, McGuinty said.
"I just don’t think it would be fair to vote during the course of the summer," he said.
"I think we should allow Ontarians...to enjoy their summer, but having said that, I think we are in a sooner-rather-than-later mode."
McGuinty said he's not worried the opposition parties will hammer the Liberals over their wage dispute with teachers or the $190 million cost of cancelling a Mississauga power generating station during the byelection campaigns.
"They’ll use whatever they choose to use, and we stand to be judged in these byelections as we are as we do in general elections," he said.
"We’re prepared to defend any decisions we made."
Sorbara, 65, was first elected in 1985, quit politics after a decade but returned in 1999 as president of the Liberal Party, and was elected in a 2001 byelection.
With some of his six children and 12 grandchildren watching, Sorbara — his wife Kate at his side — said his proudest political achievement — besides helping the Liberals defeat the Conservative government in 2003 — was the introduction of a Child Tax Benefit, which provides low-income families with up to $1,100 per child each year.
Sorbara will also be remembered for introducing a health tax of up to $900 for every worker in the Liberals' first budget, breaking McGuinty's famous pledge not to raise taxes.
He had to temporarily resign as finance minister in 2005 because of an RCMP investigation into a private company, but was cleared and returned to cabinet seven months later. Sorbara resigned from cabinet in 2008.
Sorbara's resignation came after three previous attempts to quit the life of an elected politician, said McGuinty.
"He's come to me at least three times in the past and said, 'I’ve got to get out of this place. I’ve got to devote more time to my family,' and I said to Greg: 'You can't. I need your energy. I need your idealism. I need your passion,'" said McGuinty.
"Well there comes a time, as they say, when Greg’s got to fish or cut bait, and he has decided that he is going to put his family first. I respect that."
The Tories praised Sorbara's public service, but said he was part of a Liberal government that racked up a record deficit and nearly doubled Ontario's debt in nine years.
"The fact is this province is in a mess; we have a jobs crisis and a fiscal crisis," said Conservative Rob Leone.
"I think the people of Vaughan and the people of KW need to hear that message."
The New Democrats stayed on the high road, thanking Sorbara for his years of public service and holding any criticisms for another day.
"While we may not always have seen eye to eye on the floor of the legislature, I appreciate Mr. Sorbara’s determination and skill," said NDP Leader Andrea Horwath.
Sorbara's resignation leaves the Liberals with 52 seats, one fewer than the combined Progressive Conservatives and New Democrats.