The first national poll taken since Dion unveiled the proposal last Thursday found most Canadians did not know enough yet to form an opinion.
But once the policy was explained to respondents, the Canadian Press Harris-Decima survey found, close to half - 47 per cent - liked the idea, while 39 per cent said they were opposed.
The key finding, said pollster Bruce Anderson, is that Canadians who did not describe themselves as Conservatives were favourably disposed to the idea of a revenue-neutral carbon tax.
Two-thirds of Liberals, 59 per cent of New Democrats, 62 per cent Bloc Quebecois supporters and 48 per cent of Green Party supporters said they were in favour of the policy - all, except for the Green Party, by wide margins.
The Liberal green plan is also finding double-digit support among women (48 per cent in favour, 34 per cent opposed), voters under 35 years of age (61 versus 26), and in voters east of the Ontario-Manitoba border (49 versus 37), all segments the Conservatives need in order to win a majority.
"It does have the potential to be a game-changer for the Liberals," Anderson said. "For them that means establishing a ballot question that will work to their advantage and getting to a level of support on that policy that probably could be as low as 50 per cent if it's the right 50 per cent."
The telephone poll of 1,000 was conducted between June 19 and 22 and is considered accurate to within plus or minus 3.1 percentage points, 19 times out of 20.
Of those who had already formed an opinion, 14 per cent were in favour and 17 per cent against.
Among individuals who described themselves as Conservative supporters, 62 per cent said they opposed the concept as explained and only 32 per cent were in support.
Anderson noted that the Conservative attacks on the policy, including Prime Minister Stephen Harper calling it "crazy," likely had an impact on driving up opposition initially.
But he cautioned that Harper may be playing into Liberal hands by helping to make the environment a key ballot question, especially if he is unable to convince non-Conservatives that his party has a better plan.
"If I were them I would not be wanting a war on this," he said. "The real challenge for the Conservatives is that the more they talk about it, the more they risk ending up with a campaign on the weakest card in their hand and the strongest card in the Liberal party hand."
But the Green Shift is far from a sure thing for the Liberals, he added.
The survey results showing strong initial support among non-Conservatives came after respondents were read a description of the policy that, while it used fairly neutral language, nevertheless presented the policy as the Liberals would wish.
Respondents were read this passage: "The Liberals are calling their policy A Green Shift. The main elements are putting a tax on carbon or greenhouse gas emissions, and using the money raised by this tax to reduce income and other taxes, to provide financial support for those less well off and to invest in green technologies. The tax increases will be phased in over four years and will not apply to gasoline. Based on this description, would you say this is a policy you strongly support, support, oppose or strongly oppose."
Anderson said the Conservatives could still succeed in convincing a majority of Canadians that the tax would not be revenue neutral, or that gas prices would skyrocket.
But he added that it could be a pyrrhic victory if the argument falls on deaf ears among those not already in the Conservative camp.
"You've got to look at that and say, 'Am I really going to carry the day that this is insane? Am I going to persuade people that this is more than my own partisan agenda?' "
