Conservative Leader Stephen Harper went on the offence Thursday, attacking the Liberal Green Shift plan and criticizing leader Stephane Dion for stumbling during a media interview.

Harper, speaking at a campaign stop in Vancouver, told supporters Thursday that a Liberal win on Oct. 14 would drive Canada's economy into recession because Dion would raise taxes and increase government spending.

"If you elect Prime Minister Dion, who would impose and raise carbon taxes and run deficits, interest rates will go up," said Harper, who continued to present his party as the best choice to manage Canada's economy during a time of global financial turmoil.

He also presented Canadian voters with a stark choice: stability or risk.

"There will either be Prime Minister Dion, who will tackle our economic problems by increasing spending that we cannot afford and increasing taxes to pay for it. Or our government, which will keep spending under control and keep taxes going down."

At the start of an interview CTV Atlantic anchor Steve Murphy, Dion asked for a question on the economy to be repeated. The Conservatives seized on the incident, and Stephen Harper emerged to scrum with reporters Thursday evening about it.

"When you're running a trillion-and-a-half-dollar economy, you don't get a chance to have do-overs, over and over again," Harper told reporters.

"I think what this incident actually indicates very clearly is Mr. Dion and the Liberal Party really don't know what they would do on the economy."

Harper's renewed attack on the Liberals comes after a dismal week for the Tories, who have been hammered by opposition parties over their handling of the growing global financial crisis.

But after a promising week which saw his Liberals' close a once-commanding Conservative lead, Dion was forced to shift to the defensive on Thursday at a campaign stop in Nova Scotia, where Premier Rodney MacDonald warned voters that a carbon tax would cost the province around $600 million per year.

The Conservatives were also buoyed by recent statements from the World Economic Forum which ranked Canadian banks as the world's strongest: news that echoed Harper's opinion that Canada will weather the economic storm.

Worse yet for the Liberals, Dion had to contend with recently-published comments from star candidates - and leadership rivals - Bob Rae and Michael Ignatieff which suggested a deep global recession would force a Liberal government to rethink the carbon tax.

Later in the day, however, Rae and Ignatieff issued a joint statement of support for their leader, and Dion hit back at critics and said that many economic experts support his plan.

"It's what economists are asking us to do. It's good for the economy. Countries that have done their green shift, their (economies) outperform countries that didn't. We need to do it in Canada."

Dion added that any tax hike on carbon would be offset by lowered income taxes. For example, a regular family with an annual income of $60,000 would get a $1,300 income tax break when the plan is fully implemented in four years, he said.

"If I'm proposing it, it's because I'm convinced that it's good for Nova Scotia."

Harper's renewed carbon tax attack came as a top U.N. official warned Thursday that global financial problems could stall efforts to fight climate change.

Yvo de Boer, executive secretary of the U.N. climate secretariat, told The Associated Press that "you can't pick an empty pocket.

"I think that the financial crisis is going to make it more difficult for industrialized countries to make public resources available for cooperation with developing countries," he said.

"Many industrialized countries at the moment are propping up their financial sector and they're borrowing money to do it, which means to my mind that there's going to be a constraint on the capital market, and that potentially can impact the negotiations."

Still, it wasn't all bad news for Dion, as two Green Party hopefuls in Quebec threw their support behind the Liberals. Danielle Moreau, a candidate the riding of Longueuil-Pierre-Boucher, even quit the race and backed Liberal rival Ryan Hillier.

"We must be realistic," said Moreau. "What I want is that Harper is out."

With files from The Canadian Press