Kathleen Wynne says she is resigning from her roles as the province's Minister of Municipal Affairs and Aboriginal Affairs, opening the door to a potential run for the leadership of the Ontario Liberal party.
Premier Dalton McGuinty made a surprise announcement two weeks ago that he was stepping down after 16 years as Liberal leader and nine as premier.
He has specified that anyone seeking to run for the party's leadership would have to resign from cabinet.
Ms. Wynne, who has long been rumoured to be a potential leadership contender, says she will be making an announcement on Monday, but hasn't provided any further details.
Ms. Wynne has held her Municipal Affairs and Aboriginal Affairs portfolios since October 2011.
Several other potential leadership candidates are said to be considering a bid, including former MP Gerrard Kennedy, who lost to Mr. McGuinty in 1996 by just 140 votes.
The Ontario Liberal party will decide on a new leader on Jan. 25, 2013.
Mr. McGuinty has said his successor must decide when to bring back the legislature which he prorogued as he stepped down.
Observers predict the leadership convention is likely to be followed by a throne speech, budget and another prorogation to allow for a general election.
Mr. McGuinty said he prorogued the legislature to allow time for his embattled government to negotiate with unions and the Progressive Conservatives on a public-sector wage freeze.
But it also brought all legislative business to a standstill and killed planned committee hearings into cancelled power plants in Oakville and Mississauga. The opposition parties have repeatedly accused Mr. McGuinty of proroguing to avoid more bad publicity over the decision to cancel the gas plants.
Liberal leadership candidates face a deadline of 5 p.m. on Nov. 23 to submit their leadership forms.