OTTAWA — Former Ontario premier Dalton McGuinty will announce Wednesday that he is resigning his Ottawa South seat at Queen’s Park.

The longtime MPP has represented the riding since 1990 and served for nine years as premier, stepping down in October and proroguing the legislature.

McGuinty, who’s only been spotted in the legislature twice this year, skipped the final vote on the province’s budget Tuesday and has been ducking media calls for weeks.

In an email sent late Tuesday afternoon — less than two hours after the minority Liberal government passed the province’s budget with the help of the New Democrats — McGuinty’s executive assistant Chike Agbasi said, “Now that this session of Parliament has concluded, Mr. McGuinty will be issuing a statement in the morning.”

Multiple sources confirmed the statement would contain the 57-year-old’s resignation.

John Fraser, McGuinty’s lieutenant in his Kilborn Avenue constituency office, is the only candidate who has announced his intention to replace the former premier.

Fraser did not respond to requests Tuesday for comment.

A nomination meeting will be held June 20.

Voters in Ottawa South could be casting a ballot sometime in September to coincide with by-elections in several other Ontario ridings.

Former finance minister Dwight Duncan and former energy minister Chris Bentley both stepped down on Feb. 14.

Rules stipulate that an election must be called within six months of an MPP’s resigning, so the government must call an election by Aug. 14, and the election itself must be held between 28 and 36 days after that.

Although the Ottawa South byelection doesn’t have to be held on the same date as the others in London and Windsor, it’s widely expected that will be the case.

That represents a mini-election for the province and a chance to test McGuinty’s successor in the premier’s office, Kathleen Wynne, said Lisa MacLeod, the Tory MPP for Nepean-Carleton.

She and McGuinty have been adversaries in the legislature for years and MacLeod said McGuinty’s choice to step down as MPP — which she called for earlier Tuesday during Question Period — is the first time in her career that he’s actually listened to her.

“He should have done this when he prorogued the house and resigned as premier,” she said from the train back to Ottawa.

Despite his decision to vacate his seat, MacLeod said, the stain of the gas plant cancellations and last week’s damning report from the province’s Information and Privacy Commissioner about senior Liberal aides deleting emails still hangs over McGuinty.

Cancelling the two Toronto-area gas-fired power plants will cost taxpayers at least $585 million and has been a constant source of trouble for Wynne’s fledgling government.

Immediately following his appearance before the gas-plant probe last month, McGuinty told reporters he intended to sit in the legislature until the next election.

His sudden resignation announcement has led some to speculate that he might be leaving Queen’s Park earlier than expected for a new job.