About 600 people turned out to an all-candidates debate in Antigonish, N.S., Monday night that featured Green party Leader Elizabeth May squaring off against Defence Minister and Conservative incumbent Peter MacKay.

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Green party Leader Elizabeth May gestures while speaking as Conservative candidate Peter MacKay raises his hand to rebut during an all-candidates debate Monday at St. Francis Xavier University. ((Mike Dembeck/Canadian Press))

The niceties in the two-hour debate at St. Francis Xavier University were dispensed with almost immediately, as MacKay fired the first shot against May's support of the Liberals' proposed carbon tax, the CBC's Stephen Puddicombe reported from the event.

"This is not a time to experiment with wild schemes or new, risky experiments with our economy," he said.

May swung back, telling MacKay he had his facts wrong. She then accused the Conservative government and MacKay of deserting Canada's shipbuilding industry.

"When we're buying ships for the Canadian navy and the coast guard, they should be built in Canada by Canadians and fuelling our economy," she said.

Five candidates are running in Central Nova, but many see this race as a three-person contest between MacKay, who has held the riding for more than a decade, May and NDP candidate Louise Lorefice.

Lorefice also fired a round or two that delighted the audience, particularly about tax cuts under the Conservatives.

"I have never met a woman on the doorstep that said, 'Thank God for that one-per-cent cut in the GST because now I can pay my bills,' " she said to cheers.

May attacked MacKay relentlessly during the debate, including over last year's closure of the TrentonWorks railcar plant, the Afghanistan mission and the Atlantic accords.

"TrentonWorks wouldn't be here at all if it weren't for free trade," MacKay said.

"In 1928?" May interjected.

"No, in 1990," he replied.

May also interrupted MacKay when he said was "very proud to say that it was a Conservative government that led the effort against the apartheid in South Africa."

"I'm afraid another correction is in order," May responded. "Mr. Harper's conservative-style government had nothing to do with ending apartheid. It was a Progressive Conservative government."

But May was forced on the defensive when pressed about a deal the Greens made with Liberal Leader Stéphane Dion to ensure no Liberal candidate ran against her in the riding.

She said she believes Canadians and the environment would be best served by a minority government with Dion's Liberals at the helm and "enough Greens and NDPers to keep them all honest in Ottawa." 

MacKay defended Canada's role in Afghanistan, saying Canadian troops have accomplished a great deal during the mission, including building schools and immunizing hundreds of thousands of children.

"That's what we are doing in Afghanistan, not leaving them to the vicious repression they faced under the Taliban," he said to applause.

But a day after a British general in Afghanistan said the war there can not be won, Lorefice said she was very proud to represent the only party opposed to the Afghan mission from the beginning.