TORONTO - Ontario voters head to the polls next month for the third time in less than a year as the Liberals seek a third majority, but it's a very different political landscape than the last provincial election in 2007.

There were major changes to Ontario's political map in the May 2 federal election, with the Conservatives making big inroads in traditional Liberal strongholds in suburban Toronto, raising hopes for their provincial Tory cousins in the Oct. 6 vote.

"If you look in terms of the federal election, there certainly was a sense in parts of the country that the Conservative message was an appealing message," said Prof. Caroline Andrew of the University of Ottawa. "I think there also is a sense of time for a change in the electorate, a sort of accumulation of sometimes quite small irritations and so it builds up to time for a change."

The opposition parties want to cash in on what they see as unpopular Liberal policies, especially the Green Energy Act, which pays much higher rates for solar and wind power and is blamed by the Tories and NDP for sending hydro bills soaring.

There is also small but vocal opposition to the wind farms in some pockets of the province, especially southwestern and eastern Ontario, where there are strong challenges to the Liberals' energy plan.

Twenty of the 107 seats in the legislature have no incumbent seeking re-election and they have the potential to be wide-open races, said Henry Jacek, professor of political science at McMaster University in Hamilton.

"To start to look at the vulnerable ridings for anybody you start to look at the open seats, and 14 of them are Liberal so immediately you start to look at those," Jacek said.

"After that, I would think the most interesting seats are ridings where there's a federal Conservative MP and it has been held by a Liberal (provincially)."

Seven ridings with Conservative MPs that are held by the Liberals provincially are in vote-rich suburban areas near Toronto with large ethnic populations that voted Tory in big numbers on May 2.

"Brampton and the Mississauga ones really are critical," said Jacek.

Suburban ridings held by the Liberals on the other side of Toronto could be vulnerable, especially Scarborough Centre, which has voted for the winning party in every election in the past 40 years.

Polls show the governing Liberals struggling in popular support, especially in the north and southwestern Ontario, where unhappiness over industrial wind farms has generated local protest movements.

Cabinet minister Glen Murray could be in trouble in Toronto Centre, where the Tories have dropped flyers that attack the New Democrats but completely ignore the governing Liberals. The NDP says it's a sign the downtown Toronto riding could definitely tip their way.

The Tories must take southwestern seats like Huron Bruce, home of Agriculture Minister Carol Mitchell, if they hope to defeat the Liberals this fall, said Jacek. Not everyone in rural areas is upset with Premier Dalton McGuinty's green energy policies, he added.

"McGuinty, for a city boy and a lawyer, he's worked very hard on farmers, put in a lot of effort in terms of policy, visiting them, picking key farm leaders to embrace them and keep them in the fold, so he's worked very hard on that," said Jacek.

"The Conservatives know they've got to win those farm seats, they've got to take Huron Bruce away from the ag minister. To form the government they've got to take those southwestern Ontario Liberal seats."

Liberal cabinet minister Sandra Pupatello is not running again in Windsor West, but if the Liberals can't hold that riding it's more likely to go New Democrat than Tory.

The Progressive Conservatives have high hopes of making gains in northern Ontario, where Liberal fortunes have been falling in part because of soaring electricity prices that many blame for driving mining and forestry jobs out of one-industry towns.

Jacek predicted it's the New Democrats who will benefit from any Liberal slippage in the north, not the Conservatives.

"I do not believe the Tories are going to do much in the north, but the NDP will," he said.

There will be an interesting showdown in the Lindsay area between Tory Laurie Scott and Liberal Rick Johnson. Scott gave up her Haliburton-Kawartha Lakes-Brock seat after winning in 2007 so former PC leader John Tory could run in a byelection, but Tory lost to Johnson, so this one is almost a battle of two incumbents.

"That's going to be a battle royal up there," said Jacek.

Progressive Conservative Leader Tim Hudak has sought out some star candidates, such as Hamilton television personality Donna Skelly in Ancaster-Dundas-Flamborough-Westdale, but he upset local party organizers in the process.

"They pushed aside the old boys to put in Donna Skelly, but she's never run for office before," said Jacek.

"That's going to be a fun riding to watch, and that's the kind of riding that's going to be really interesting across the province, where the Tories are not that far behind (the sitting Liberal)."

The Green party is fielding a full slate of candidates in hopes of finally winning a seat in the legislature. Green Leader Mike Schreiner is running in Simcoe-Grey, but veteran Tory Jim Wilson is not expected to have any trouble keeping the Barrie-area riding.

The New Democrats also made big gains in the federal election, and while most of them were in Quebec, the party's brand has never been stronger or more recognizable. The Ontario NDP are confident they too will return with bigger numbers after the fall election, and Jacek agrees, predicting the New Democrats will pick up 10 to 15 seats.

"I'm sure the Liberals are going to lose a number of seats to the NDP, but they have to keep their losses to the Conservatives down as best they can, even if it means they go into a minority and they have to make some sort of deal with the NDP," he said.

"How many Liberal seats will go over to the Conservatives is strategically the big question."