The byelections in Windsor, London, Ottawa and two Toronto-area ridings were triggered by the resignations of five Liberals since Wynne took over as premier in February, including former premier Dalton McGuinty.
Wynne will call all five byelections Wednesday, Liberal sources said, even though she could wait until December to call the votes in Ottawa-South, Scarborough-Guildwood and Etobicoke-Lakeshore.
It's an "unusually large number of byelections" to be held all at one time, especially when people often use such opportunities for protest votes against governments, said associate professor of politics Bryan Evans of Ryerson University in Toronto.
"Byelections are an opportunity to punish a government but not defeat it, and come the general election, vote for that government if it is deemed better than the alternatives," Evans said.
Despite the $585 million spent to cancel gas plants in Oakville and Mississauga, which the opposition parties say were scrapped to save Liberal seats in the 2011 election, the Progressive Conservatives downplayed their chances in the byelections.
"We have to remember that these five byelections are being held in ridings that the Liberals have held for quite some time, so they do have a strategic infrastructure advantage in terms of their campaign team," said PC critic Lisa MacLeod.
The NDP want voters to punish the Liberals for the gas plants and financial issues that prompted a police probe of the Ornge air ambulance service, even though the NDP supported the minority government's budget instead of joining with the Tories to trigger a general election.
"This is a government that's careening from scandal to scandal, the gas plants being the latest of many scandals, and absolutely the voters should hold them to account," said New Democrat Cheri DiNovo.
"People are very concerned about the integrity of this government."
Three of the byelections can be tied directly to the gas plants scandal: London-West was held by former energy minister Chris Bentley; Ottawa-South was McGuinty's riding; while Etobicoke-Lakeshore in Toronto was one of the seats the opposition parties say was saved in 2011 by scrapping the energy projects.
However, deputy premier Deb Matthews said she thinks the byelections will be decided by local issues, not by anger over the gas plant scandal.
"I've long stopped trying to predict what's going to be the big issue in an election, but judging from my community, it's not a big issue," Matthews said in an interview.
"I think that the issues in the ridings will be most important, particularly who can best represent the riding at Queen's Park."
The Tories and NDP cried foul after it was announced the Liberal candidate in London-West would be Ken Coran, the former head of the Ontario Secondary School Teachers' Federation who last year boasted about helping defeat the Liberals in a byelection in Kitchener-Waterloo.
Wynne's decision to reward teachers with more money after they fought against the government's wage freeze legislation, known as Bill 115, was a payoff to Coran to get the powerful teachers' union back on side with the Liberals, said MacLeod.
"It cost Kathleen Wynne $114 million to get a Liberal candidate in London. It cost them over $500 million to save five Liberal seats in the last election," said MacLeod.
"I think the public will draw a very stark conclusion that Kathleen Wynne and her predecessor, Dalton McGuinty, will use public money to advance their own political gain."
The New Democrats said the Liberals should not expect teachers to vote for them in the byelections just because Coran is now a candidate for the governing party, warning people won't like a union boss "turning" on his membership.
"I think it's somewhat shameful that you have a union leader running for an anti-union party, a union leader who is out protesting Bill 115 turns around and runs for the government that brought it in," said DiNovo.
The Liberals were one seat short of a majority government before the five resignations, so the outcome of the byelections will not change the balance of power in the legislature.
Also on HuffPost