OTTAWA — Whether or not it wins a seat in the next federal election, the Green party has demonstrated its potential ability to wreak big-time havoc on the election outcome in individual ridings.

Just ask Stephane Dion.

The Liberal leader came within a hair of losing a Vancouver fortress -- and perhaps his hold on his party -- as his troops bled away votes to the Greens in one of four byelections Monday.

In other races, the seatless environmentalist party chipped away at support for the NDP -- beating New Democrats in one Toronto riding while finishing less than a percentage point behind in two other races.

The Greens even beat the Conservatives in Toronto Centre.

Party Leader Elizabeth May said she has never calculated the number of ridings nationally in which her party could steal enough votes to help determine the outcome.

She said her party can win six to 12 ridings -- and that's all she cares about.

"I'm not the least bit interested in the Green Party of Canada playing any kind of spoiler role. Someone in the party might have done the math. But if they did, they haven't told me.''

However, pollster Bruce Anderson said the Greens can hurt every party in some parts of the country, while helping them elsewhere.

"I don't think there's any doubt, the Green party will play this (spoiler's) role,'' said the president of Harris-Decima.

"The Green party is drawing strength from the NDP, from the Liberals, and from the Conservatives.''

Anderson said it's not clear how many seats could get flipped thanks to a strong Green performance -- and where those seats are.

"All of the traditional rules about how vote splits work to advantage one party or the other . . . all those rules need to be completely re-evaluated. The math isn't going to get simple soon.''

Fearing the consequences on their own party, New Democrats have long downplayed the possibility of a Green breakthrough. They continued to do so Tuesday.

One NDPer said the Greens campaigned hard in the four byelections and spent resources they could not afford in a general election.

"They bet the farm on these byelections and I can't imagine they'd be anything but disappointed,'' said B.C. MP Peter Julian.

"They ran expensive campaigns. And what do they have to show for it? Well, 13, 12, six per cent.''

May scoffed at the suggestion that the Greens spent beyond their means. She said she's not aware that a single penny flowed from national headquarters to any of the four Green candidates and said campaign funds were locally raised.

"Our candidate in Willowdale -- who did better than the NDP -- didn't have a single paid staff person. He didn't have an office,'' May said.

While the NDP jabbed at the Greens, Dion seemed happy that to give up votes to the party rather than to the Tories.

"I think the party that won the most votes is by far the Green party. It took a lot of our vote,'' Dion said.

"We have a very lively and healthy relationship of co-operation and competition between (May) and me. I welcome the role of the Green party in our electoral system, in our political system.''

Dion faced criticism within his own party when he signed a non-aggression pact with May last year. He promised not to run a candidate against her in Nova Scotia and she essentially offered her endorsement of him to become prime minister.

But if the Greens had stolen another 150 or so votes from the Liberals in Vancouver, May's pick for prime minister would have lost his party's most reliable fortress west of Ontario and may have faced calls for his resignation.