Former finance minister Greg Sorbara as stepped down has a member of the Ontario legislature, but will stay on as chair of the Liberals' election campaign.
Ontario Premier Dalton McGuinty and Sorbara made the announcement at Queen's Park on Wednesday morning.
Sorbara quit the cabinet a few years ago but remained an influential adviser to McGuinty and co-chaired the Liberals' re-election campaigns.
The resignation of the veteran Liberal from his Vaughan riding means McGuinty now has to call two byelections.
The premier must also call a vote in Kitchener-Waterloo to replace Conservative Elizabeth Witmer, who he appointed chair of the Workplace Safety and Insurance Board.
Sorbara's resignation leaves the Liberals with 52 seats, one less than the combined Progressive Conservatives and New Democrats.
(The Canadian Press)