Saying he wants to give premier-designate Kathleen Wynne a free hand, Finance Minister Dwight Duncan announced Thursday he was resigning and would leave the Ontario legislature next week.

"Renewal of the party is extremely important," Duncan told reporters gathered at Queen’s Park Thursday morning.

"I'm very proud of the fact that I was Dalton McGuinty's guy. I always will be," he said.

"I think Kathleen needs a free hand. There are a lot of talented people in our caucus who have not had the opportunity to serve in cabinet, (who) can help put a fresh face on the government."

That fresh face, he said, will help Wynne build a coalition she needs to get the minority government back in a majority position. Governments have a natural lifespan of about eight years unless they renew, he noted.

Earlier Thursday, Duncan announced on social media he would quit as the member for Windsor-Tecumseh, effective Feb. 14.

"It's been the honour of a lifetime to have served my constituents ... and the people of Ontario," he tweeted.

Duncan, who supported Sandra Pupatello during the Ontario Liberal leadership race, had already made it clear he intended to resign his seat soon.

While he's had several offers, Duncan said he hasn't accepted any new jobs yet on the advice of the integrity commissioner, who advised against doing so prior to leaving office.

He has "left the door open" to running federally although "I don't know that I will ever walk through that door," he said.

Duncan said he would be helping Justin Trudeau out in his bid for the federal Liberal leadership.

"I am going to be helping Justin out, a lot. I've been quite involved, up to date, and I'll be doing more in the next few weeks," said Duncan.

The federal Liberals choose a new leader in April.

"It's been a great run," he said, noting he first became interested in politics back in 1972.

The byelection to fill his seat in Windsor-Tecumseh, which he has held since 1995, will be "very competitive," he predicted, adding that he hasn't groomed a successor in the riding. Nor has he offered any advice on who his successor should be in the ministry of finance.

A key issue for Ontario's next finance minister will be the province's debt, he warned. Duncan also urged an end to the name-calling and for a more "adult" debate on whipping the country's finances in order.

Since 1990, four governments of three political stripes have doubled the province's debt, he noted. The debt was only reduced in one year, he said, and that was due to an accounting change.

"We've got to change the political culture," Duncan told reporters.

Ontario's deficit for the fiscal year ending March 31 will be $11.9 billion.

There are difficult choices ahead, Duncan said, and major tax cuts aren't in the financial forecast. The unemployment rate is another big concern.

"Too many people are still not working in this province," he said.

While some might blame him and McGuinty for job losses in Ontario, it's a phenomenon that's going on everywhere, he said.

"Hopefully we'll see an improvement in vehicle sales in the U.S., in the U.S. economy, and that will help lift both the Ontario and Canadian economies."

Interest rates are a "ticking time bomb" for Ontario for both the government and consumers, he said.

Being the finance minister is "a very lonely job," but help for the auto sector, the HST and reforming Ontario's tax system to make it more competitive are what Duncan cites as his achievements in the post.

Duncan lost when he ran against McGuinty for the Liberal leadership in 1996 but became his finance minister after Greg Sorbara bowed out.

McGuinty released a statement thanking Duncan for his "steady hand" and many years of service.

"Dwight Duncan was the longest serving Finance Minister in the modern era and Ontario is better for it - stronger, fairer and more prepared for a future of constant change and ever-growing opportunity," he said.

McGuinty praised Duncan for reforming Ontario's tax system, helping harmonize sales taxes with the federal government and for working to protect the auto industry during the recession.

"Dwight's steady hand has set our province on a sure path to a balanced budget while protecting the gains we have made together in health care and education. Today, thanks to Dwight's leadership and the hard work Ontarians do every day, Ontario is among the top destinations in North America for foreign investment."

Rick Bartolucci also announced Thursday he would not run in the next election and had asked to be removed as minister of northern development and mines when a new cabinet is sworn in next Monday. He said he would retain his seat until the election is called.

Bartolucci was elected as Sudbury's MPP in 1995 but entered politics in 1979 at the municipal and regional level.

But he said it's time to refocus his priorities including spending more time with his family _ a decision he made over Christmas during a vacation to Florida.

- With files from The Canadian Press