Sept. 9 (Bloomberg) -- Canadian Prime Minister Stephen Harper pledged to cut fuel taxes for shipping companies if he wins the Oct. 14 election and said opposition plans to tax energy would undermine a slowing economy.

The governing Conservatives would reduce the country's excise tax on aviation and diesel fuel by half, saving shippers in all modes of transport about C$600 million ($562 million) a year, Harper said today.

``At a time when Canadians are concerned about affordability and energy prices are rising, we should be doing what we can to lower prices,'' Harper, 49, told reporters today at a produce warehouse in Winnipeg, Manitoba.

Harper is trying to frame his campaign around the economy, saying ``untested'' plans by the main opposition Liberals to tax fuel consumption would hurt growth, already projected to be the slowest since 1992 this year. Liberal Leader Stephane Dion, 52, counters that his levy proposal would be used to pay for tax cuts and increased spending, thus sparking growth.

The prime minister is seeking to take advantage of his party's strength among voters on the issue of managing the economy, plus anxiety over Dion's plan driven by near-record prices for gasoline and other fuels.

Fifty percent of Canadians believe Harper is the best leader to get the country through tough economic times, compared with 22 percent for Dion, according to a poll by Ipsos Reid published Sept. 3.

Dion's Tough Sell

The same company found opposition to Dion's plan has grown in the past month. Fifty-one percent of Canadians oppose his proposal, compared with 45 percent who support it, according to that poll. Both surveys were conducted Aug. 26-28 and had a margin of error of 3.1 percentage points.

Dion's plan for the world's eighth-largest economy calls for funding C$15.4 billion a year in spending and tax cuts through the tax on fuel consumption. Economists favor his approach to tackling climate change because of its focus on using proceeds to lower corporate and personal income taxes, Dion has said.

``Most economists would not have a big problem with a carbon tax per se,'' Doug Porter, an economist with BMO Capital Markets in Toronto, said Sept. 4 by telephone.

Harper, meanwhile, has been criticized for putting too much money into cutting so-called consumption taxes such as the diesel fuel levy. The fuel tax would be lowered from 4 Canadian cents per liter to 2 cents over the next four years.

A flagship Harper policy in the 2006 election that brought him to power was a 2 percentage-point cut in Canada's federal sales tax, a move the International Monetary Fund said should have been replaced by cuts to income and savings taxes.

`Irresponsible'

Speaking to supporters at a campaign rally in Napanee, Ontario, today, Dion, 52, called Harper's diesel pledge ``irresponsible'' and said it would remove ``the incentive to be energy-efficient.''

Harper, whose government cut income taxes for individuals and businesses in addition to reducing the sales tax, today said the advantage of consumption tax cuts is that they're broad-based.

``It's a balanced package of taxation,'' Harper said. ``It is not a package of taxation focused on big business and high income earners. It is a package of taxation to benefit everyone, every single person in this country.''

Today's announcement wasn't the first time Harper offered tax breaks aimed at truck drivers. In last year's budget, the government increased the amount truck drivers can deduct for food and entertainment expenses.

Truck driving is Canada's No. 2 occupation for men, according to census figures released in March, with 276,200 male truckers in 2006.

To contact the reporter on this story: Theophilos Argitis in Winnipeg, Manitoba, at targitis@bloomberg.net; Greg Quinn in Ottawa at gquinn1@bloomberg.net.

Last Updated: September 9, 2008 14:45 EDT