The Ontario NDP and Liberals are saying they wouldn't work with a Tim Hudak government, raising the prospect of legislative gridlock and another snap election if the Progressive Conservative Leader wins a minority Thursday.

But the Liberals and New Democrats are leaving the door open to teaming up in a coalition after the election.

With the Liberals and PCs deadlocked in most recent polls with percentages in the mid-30s, another hung parliament appears to be a likely election outcome. Without control of more than half of the legislature, the ruling party would need to work with members of other parties to win votes for its agenda.

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Until now, New Democrat Leader Andrea Horwath has sidestepped repeated questions over whether her party would consider a coalition with the PCs. She finally ruled it out Tuesday, evoking a colourful expression favoured by the late Peter Kormos, former NDP MPP for Welland.

"I'm going to say very clearly. I call bullspit on the idea that we will have a coalition with Tim Hudak," Ms. Horwath said during a morning rally in Essex, Ont. "In the words of my good friend Peter Kormos, I just call bullspit on that."

Ms. Horwath's remarks came after the Liberals attacked her party over an interview on CP24 television on Monday evening, in which NDP finance critic Michael Prue said his party would act as "honest brokers" in the event of a PC-led government.

The Liberals characterized Mr. Prue's comments as evidence the NDP would prop up a Hudak minority. And they slammed the door shut on working with the PCs at all.

"I want to be clear that I would never support a Tim Hudak government," Liberal Leader Kathleen Wynne said Tuesday, after meeting early childhood education students at St. Lawrence College in Kingston. "Because what he is proposing would be so detrimental and would have such a negative impact on so many peoples' lives in this province, that it's not something I would countenance."

Ms. Wynne has previously said that, if Mr. Hudak wins the most seats, she will step aside and allow him to take a crack at forming government.

But her new hard line raises the prospect that she would immediately try to vote him down, which could either trigger another election or – if the lieutenant-governor agreed – allow the party with the second-most seats to take over without an election.

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At a campaign event in London, Ms. Horwath declined to rule out a coalition with the Liberals. Ms. Wynne has also left the door open to teaming up with Ms. Horwath if either wins a plurality of seats but falls short of a majority.

Mr. Hudak, who has vowed to introduce a mini-budget within weeks of taking office, would likely have to rely on the Liberals and NDP abstaining from confidence votes in the legislature to allow his government to survive in the event of a minority.

In the last parliament, the PCs voted against nearly everything the minority Liberals did, and used procedural manoeuvres to slow legislation to a crawl. The Liberals had to depend on the NDP to move most legislation, including two budgets, leading to drawn-out negotiations.

Mr. Hudak has said he will work with whatever hand the voters deal him. While touring an IT support company in Richmond Hill on Tuesday, the PC Leader told reporters he's not worried about support from the other two parties.

"What's most important is support from voters," he said.

Mr. Hudak has spent the last few days accusing the other parties of running negative, "American-style" attack campaigns. He said the fact that both of his opponents are unwilling to play nice proves his point.

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"You're seeing two leaders in Andrea Horwath and Kathleen Wynne who are telling you what they won't do. They'll tell you who not to vote for," he said.

Ms. Wynne is spending the final days of the campaign warning voters the only way to stop the PC plan to cut 100,000 public sector jobs is to vote for the Liberals.

Calling Mr. Hudak's agenda "so crazy and so wrong-headed," Ms. Wynne said Tuesday it would mean newly graduated health-care workers, personal-support workers and early childhood educators could not get jobs in their fields.

"He would be busy firing people just a little older than you and those jobs would not be there … it would slam the door on jobs for young people," she told the ECE students at St. Lawrence.