Finance Minister Dwight Duncan says he is leaving politics to give Ontario's premier-designate a "free hand'' to renew the Liberal government.

Duncan confirmed the news on his Twitter account in the early morning hours of Thursday.

"Today, I'm submitting my resignation as MPP for Windsor-Tecumseh, effective Feb 14. It's been a privilege to serve in public office. #onpoli"

In a following tweet he wrote, "It's been the honour of a lifetime to have served my constituents in Windsor-Tecumseh and the people of Ontario"

He initially told reporters back in October that he wasn't stepping down; but he would not be seeking re-election.

Some reports suggest he is on the verge of taking a job in Toronto's private sector, but Duncan says that's not the case.

Duncan told reporters that he was a key figure in Premier Dalton McGuinty's cabinet, and it's very important that incoming premier Kathleen Wynne has the opportunity to put her own stamp on the Liberal front bench.

"I've always believed ... governments have a natural lifespan in my experience of about eight years ... unless they renew,'' he said at the Ontario legislature.

"I'm very proud of the fact that I was Dalton McGuinty's guy, I always will be, but I think Kathleen needs a free hand, and there are a lot of talented people in our caucus who have not had the opportunity to serve in cabinet, (and) can help put a fresh face on the government.''

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

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 Thursday morning thanking Duncan for his 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.''

Duncan's resignation will clear the way for a byelection in Windsor-Tecumseh. He has represented Windsor-area ridings since 1995.

(w files from the Canadian Press)