The Liberal campaign decided to halt construction of a power plant in Mississauga days before last fall's election when they were behind in the polls, Finance Minister Dwight Duncan admitted Thursday.

Ontario taxpayers are on the hook for $190 million for scrapping the project the Liberals had championed and supported until it looked like they might lose the Oct. 6 election.

"This was a campaign undertaking at a time when I think we were still behind in the polls, so it required a government decision which occurred after the election," Duncan told the estimates committee.

"There was no cabinet discussion prior to the election, formal or informal, about relocation (of the power plant)."

Duncan clashed repeatedly with Conservatives and New Democrats on the committee, who insisted the decision to stop construction on the power project was motivated solely by a desire to preserve Liberal seats in the vote-rich area west of Toronto.

"Once they realized it was a political problem — the minister said it himself: 'we did this when we were down in the polls' — then all of a sudden they decided to react," said New Democrat Gilles Bisson.

"And I just think that's a bad way of doing policy."

The Conservatives said the gas plant was cancelled after growing local opposition threatened the Liberals' chances at re-election.

"I think the picture's pretty clear that this decision was a political one that was to serve the best interests of the Liberal party in order to save seats last October, and use your and my money to pay for it," said Progressive Conservative critic Michael Harris.

Duncan lost his patience with Harris at one point during their many exchanges, calling the rookie Tory MPP "a pitiful joke" for claiming the minister was comparing the gas plant with the deadly shopping mall collapse in Elliot Lake.

He later apologized, which Harris accepted.

The New Democrats released a copy of an email from Colin Andersen, CEO of the Ontario Power Authority, sent at 11:30 p.m. Sept 23, that suggested he had advance warning the Liberals were going to shut down the Mississauga plant.

The Liberal campaign sent out a press release cancelling the Mississauga project on Saturday, Sept. 24, but did not send it to any reporters actually covering their party.

The OPA confirmed Thursday that a Liberal campaign volunteer did inform the chairman of the agency's board of directors that the party was "going to make an announcement."

The NDP wondered why the OPA would be given advance notice of a political decision by the Liberals' campaign team.

"Political parties are separate to what a government is," said Bisson.

"The fact that there was a political decision made by the Liberal party that cost the taxpayers of Ontario a heck of a lot of money should concern us."

Duncan also warned the opposition parties against inflating their estimates of the potential cost of the Liberals' decision to cancel another power station in neighbouring Oakville, again because of widespread local opposition.

"Comments about Oakville at $1 billion are frankly reckless," Duncan told the committee.

The Oakville gas-fired station was supposed to be much larger than the other cancelled project, and the opposition parties expect it will cost a lot more than the $190-million tab for Mississauga.