Harper says Liberal Leader Stephane Dion was against the idea of a carbon tax for years and the fact he's made an about-face shows he has no credibility. He says Canadians should not believe claims that the tax won't affect gasoline and energy prices or hurt the economy.

Harper says the Conservative party doesn't believe in the idea of dealing with high energy prices by imposing extra taxes on fossil fuels.

He says all new taxes are designed to fill the government's coffers and the carbon tax is no different.