The three contenders for the prime minister’s office clashed in their second debate Thursday evening in Calgary, where slumping oil prices and industry layoffs framed a discussion on the economy.

NDP leader Tom Mulcair accused Conservative Stephen Harper of having a “rip and ship approach” to natural resource development, adding that Harper “put all of his eggs in one basket, and then dropped the basket.”

Harper said it is “simply false” that the oil industry’s woes represent the entire economy, and overall it continues to perform well and produce more tax revenue despite a 40 per cent reduction in small business taxes and other tax cuts.

Liberal leader Justin Trudeau said his plan also includes reduction in small business taxes, and he emphasized he is the only leader willing to raise personal income taxes on the wealthiest one per cent of income earners, to finance a cut for the middle class.

Moderated by David Walmsley, editor of The Globe and Mail, the debate drew out differences between the three established party leaders on several topics.

Infrastructure:

• Trudeau defended his plan to run three deficits of up to $10 billion to finance roads and other infrastructure, with interest rates at a low ebb and Canada’s debt relative to the size of the economy declining.

• Mulcair called Trudeau’s plan “reckless and uncosted,” while the NDP calls for steady investment over 20 years.

• Harper said over 10 years, his government has spent 15 times what the previous Liberal government spent on infrastructure. That includes record deficits for public works projects in the wake of the 2009 economic crisis.

Taxation:

• Harper said the other parties promise tax relief for small businesses, but their plans to increase Canada Pension Plan and Employment Insurance premiums amount to a payroll tax 10 times as big as their small business tax cuts.

• Mulcair said he will raise income tax from 15 to 17 per cent for large corporations, but he believes individuals are paying their fair share now. Mulcair reminded viewers that Trudeau has supported Conservative budgets, and his first vote in Parliament was to support Harper’s tax “giveaway” to big business.

• Trudeau emphasized that his is the only plan that increases taxes for bank executives and other wealthy individuals as well as on banks, while reducing income tax on the middle class.

Greenhouse gases:

• Mulcair favours a cap-and-trade system, but he avoided questions about what his system would cost the economy or consumers. The NDP will “enforce overarching sustainable development legislation,” he said.

• Trudeau defended his position that each province should address emissions in its own way. He said Mulcair wants to impose a national bureaucracy, including on B.C., which Trudeau called a world leader in use of carbon tax.

• Harper said carbon taxes are about revenues to government, not the environment. He said under his 10-year administration, Canada has seen a decline in emissions while the economy grew, adding that his government invests $1 billion a year in alternative energy.

Green Party MP Elizabeth May wasn’t invited to the Globe debate, but chipped in with videos on her Twitter account. In one, May noted that there was no discussion of “investor state agreements” such as one with China that have intruded on Canada’s sovereignty.