Monday's Munk debate on foreign policy ended with an overture to what could be the most important issue of this campaign: whether Canada should be part of the Trans Pacific Partnership, the most ambitious regional trade agreement ever undertaken.
With Stephen Harper's Conservatives almost certain to initial the agreement, which could be unveiled within the next few days, the question is whether NDP Leader Thomas Mulcair and Liberal Leader Justin Trudeau support or oppose the deal.
Based on what the leaders were saying Monday night, the question could be election-defining, the first time trade has taken centre-stage since the epic election of 1988 over the Canada-U.S. agreement.
The exchange among the leaders was itself revealing: Mr. Harper promoted his government's record of negotiating trade agreements with literally dozens of countries; Mr. Mulcair warned he would not support any agreement that weakened agricultural protections; while Mr. Trudeau promoted the idea of trade in general without making any specific commitments on the Trans Pacific Partnership.
The TPP, as it is known, involves 40 Pacific nations, including the United States and Japan, representing almost 40 per cent of the global economy. Because it also includes Mexico, the talks are also seen as NAFTA 2.0.
As well as eliminating traditional tariffs on manufactured goods, the TPP involves lowering agriculture subsidies, opening government procurement to foreign competition and protecting intellectual property.
Negotiations have dragged on for years; an attempt to wrap them up last month in Hawaii went nowhere. Time is running out for Congress to approve any agreement. Talks are underway again in Atlanta. For the Trans Pacific Partnership, it's now or never.
New Zealand Prime Minister John Key is optimistic an agreement will be reached over the coming days.
"I always said it would take one last shove by leaders to get that over the line," he told the New Zealand Herald Monday. "I think there is some growing momentum now around potentially a deal emerging from Atlanta later in the week."
But key issues remain unresolved, in particular over access to dairy markets and quotas for offshore-manufactured parts in automobiles.
New Zealand is as keen to have access to American dairy markets as the United States is to have access to the Canadian market.
Canadian dairy and poultry farmers fear the erosion of their exclusive control over the Canadian market under the quota system known as supply management.
Because about half of all dairy farms are in Quebec, it's a particularly sensitive subject for New Democrats, who represent most of the ridings where those farms are located. Rural Ontario also has a strong dairy and poultry presence.
Ed Fast, the International Trade Minister, has denied reports that Canada is willing to partly open its dairy market to American competition. But all the countries involved will need to make concessions to seal a deal this week.
And those concessions could be pivotal in determining how the Liberals and New Democrats view the deal.
In the three weeks that remain before the election, Mr. Harper will seek to define the choice: a Pacific, globalized, outward-looking Canada under the Conservatives versus a closed, protectionist and declining Canada under the Liberals or the NDP.
Specifically, the Conservatives will accuse the NDP of being willing to shut Canada off from the world; Mr. Mulcair will accuse the Conservatives of betraying farmers, and Mr. Trudeau will promise that a Liberal government will somehow negotiate a better deal.
Let the debate begin.