TORONTO - Mainstream political parties vying to become the next Ontario government must bone up on their green policies and give voters more than "empty promises,'' a coalition of Canada's major environmental groups said Monday.

The environment has overtaken health care as the top concern for voters, said the coalition which vowed to use their Ontario members in key provincial ridings to put the green policy front and centre come Oct. 10.

But the coalition -- which includes Greenpeace, the World Wildlife Fund, the Pembina Institute and Environmental Defence _ said a poll they had commissioned shows no one mainstream political party has convinced voters that they are the greenest option.

"There is real hunger for some significant ambition from our leaders,'' said Rick Smith, executive director of Environmental Defence. "It's time for the political parties to think big and to deliver.''

While the Liberals have made a series of environmental announcements -- setting greenhouse gas emission targets and putting the closure of Ontario's coal plants by 2014 into law -- environmentalists are still waiting to see both the Liberal and NDP election platforms.

The Conservatives are promising rebates to encourage the reduction of greenhouse gas emissions and have set targets that to cut emissions by 10 per cent below 1990 levels by 2020.

Bruce Cox, executive director of Greenpeace, said all the parties have a tremendous opportunity to woo the growing number of voters concerned about climate change.

"No party has a lock on this election,'' Cox said. "It's a tight campaign. In order to win the needed support, the (parties) are going to have to be talking about the issues that are important to voters _ environment being the number one issue.''

Ontario voters aren't impressed by the what the political parties have pledged so far on the environment, said Cox.

"We're hoping that some party will break from the pack and environmental issues will become key in the election,'' he said.

But Nelson Wiseman, political science professor at the University of Toronto, said it's not hard to commission a poll that shows people care about the environment. Just because people say they are concerned about the environment, when asked, doesn't mean they will vote based solely on that issue, he said.

The state of Ontario schools, people's perception of crime, how well the Liberals have governed and how people feel about the political leaders are much more likely to influence the Oct. 10 vote, Wiseman said.

"You can always get people's opinions on an issue, but does it matter?'' Wiseman said. "People respond positively by saying 'we care about the environment' but... I don't think that's what the ballot is actually cast on.''

An Environics poll commissioned by the coalition suggests 20 per cent of the 1,160 eligible Ontario voters polled feel the environment was the "most important'' election issue. Health care was a close second place at 18 per cent.

One-third said they didn't know which mainstream political party had the best approach to the environment.

The results of the poll, conducted the first week of July, are considered accurate to 3.1 percentage points, 19 times out of 20.

The coalition presented all three political parties with the results of their polling Monday, adding they have just over 200,000 members in key ridings across Ontario which they will use to press for environmental policy during the upcoming election campaign.