Stephen Harper's Conservatives may have to change the script for their smear campaign against Tom Mulcair, at least when it comes to the NDP leader's supposed anti-trade "extremism."

Under Mulcair, the New Democrats have adopted a more open approach to trade deals, one that could rob the Conservatives of one of their preferred lines of attack.

The NDP has already backed one free trade agreement, with Jordan, and is pushing for expedited negotiations on a deal with Japan.

And it's arguing that Canada should give priority to negotiating similar pacts with India, Brazil and South Africa.

Moreover, the party has dropped all talk of rescinding or reopening the North American Free Trade Agreement, a deal the NDP has stridently opposed in the past.

And it's urging the World Trade Organization to re-start global trade talks, which the NDP used to protest against.

"The NDP have always been and are very vigorously pro-trade," NDP trade critic Don Davies insisted in an interview.

Still, he conceded there's some truth to the Tory charge that — until recently — New Democrats haven't seen a single free trade deal they could bring themselves to support.

"I think our position in the past on trade deals has been to look at a trade deal, find three or four things we don't like and then vote against it," Davies said.

"I'm not sure that that's the proper way to proceed because any trade deal has pros and cons to it ... There's going to be costs to our economy and benefits to our economy."

But all that has changed under Mulcair. Now, Davies said the party's policy is to weigh the pluses and minuses of each deal and determine if "overall it's a net benefit" to Canada.

Government not focused on 'key economies with strategic value': Davies

That said, the NDP are not about to go all gung-ho, supporting trade deals with just anybody. New Democrats intend to be more selective and strategic than the Conservatives, whom Davies accuses of recklessly signing deals with any willing partner — nine of them since 2006, including Colombia, Peru, Chile, Costa Rica, Panama, and Honduras, which Davies said are "not key economies with any kind of strategic value for Canada."

Davies said his party supports negotiating deals with developed countries whose economies are beneficial to Canada and which have high labour and environmental standards.

On that score, he said: "I don't think you could get a better partner than Japan.

"We think we have complementary economies. The Japanese have extremely high standards across the board ... (in terms of) quality of goods, environmental standards, labour standards and they're a mature democracy."

In pushing for fast-track negotiations with Japan, the NDP risks alienating at least one traditional labour constituency — the Canadian Auto Workers union, which is opposed to a deal on the grounds that Canadian car companies don't have the same access to the Japanese market as Japanese cars makers do in Canada.

But Davies said he's told the CAW and car manufacturers that "the only way we're going to make progress on that is to talk and that's even a further reason to expedite talks with Japan."

The NDP also supports, in principle, a trade agreement with the European Union, which Davies said would make "an excellent partner."

The party is concerned that the negotiations with the EU are entering the endgame with little transparency about what's at stake — particularly given the possible impact on prescription drug prices in Canada.

The Canadian Press reported Tuesday that the Conservative government is poised to agree to increased patent protection for brand-name pharmaceuticals as part of the ongoing talks — a measure that could cost as much as $900 million a year.

The NDP will wait to judge the deal in its entirety, Davies said.

After Japan and the EU, the NDP believes priority should be given to pursuing agreements with developing countries that are on "positive trajectories" when it comes to democratic, labour and environmental standards — places like India, Brazil and South Africa.

'Leopard can't change its spots'

While Mulcair has presided over a fairly dramatic shift in his party's trade policy, the Tories are unlikely to stop accusing the NDP of being anti-trade extremists any time soon.

A spokesman for International Trade Minister Ed Fast scoffed at the idea the NDP are suddenly open to trade: "As they say, a leopard can't change its spots."

Mulcair has reinforced that skepticism with his position on a controversial foreign investment agreement with China. He's vowed that an NDP government would rip up the agreement if it concluded it was not in Canada's best interests.

That prompted a recent heated exchange between Prime Minister Stephen Harper and Mulcair in the House of Commons, reminiscent of the rhetorical excesses that marked debate over the Canada-U.S. free trade deal almost 25 years ago.

"The NDP says that it is for trade but it has opposed trade with anybody," Harper charged. "The NDP even said that it was a sell-out for Canada to have a free trade agreement with the United States.

"That kind of extremism on trade is why Canadians will never entrust economic policy to the NDP."

Retorted Mulcair: "The New Democrats support trade. We just do not support selling out Canada."