Both winners of the New Hampshire primary oppose the North American Free Trade Agreement and say they want to scupper the deal should they win the presidency.
That idea faces monumental political and legal obstacles, though, starting with the fact that Donald Trump and Sen. Bernie Sanders are still far from winning their respective party nominations, let alone the White House.
But they've served notice that they want to end the 1994 agreement that had wide-ranging consequences on trade among Canada, the U.S., and Mexico.
"We will either renegotiate it or we will break it," Trump told CBS last fall, panning the deal as a disaster. "Every agreement has an end."
He says he likes free trade in theory — but the current deals are no good. However, much like his proposal to kick out illegal migrants and ban Muslim travel to the U.S., Trump is stingy with specifics.
Sanders has been consistent. He's opposed the trade deal since it was first signed and even staged a memorable protest against NAFTA early in his congressional career.
He introduced a bill that would have slashed the salary of American politicians — to harmonize them with their Mexican counterparts — so they could feel the impact they were imposing on workers.
"The essence of NAFTA is that American workers will be forced to compete against the desperate and impoverished people of Mexico who earn a minimum wage of 58 cents an hour," Sanders told the House of Representatives, where he sat before entering the Senate.
"It is only appropriate that we, the Congress, lead by example ... (Mexican politicians) earn the equivalent of $35,000 a year... If we're going to ask American automobile workers and dairy farmers and truck drivers to be competitive with counterparts in Mexico, then the salaries of the U.S. Congress should be competitive with the Mexican Congress."
Unsurprisingly, his 1993 bill failed. NAFTA, on the other hand, passed.
Now Sanders' presidential election platform promises to "reverse" trade policies like NAFTA. One trade lawyer says his legally trained ears detect the sound of wiggle room there — reversing trade policies could mean any number of things.
Mark Warner says he's skeptical either candidate would cancel the deal.
It would be mind-bogglingly complex, he said. Even if a president provided six months' notice that the U.S. was pulling out, elements of NAFTA have since been embedded in the World Trade Organization agreement.
Another problem: old tariffs couldn't just snap back into place. The U.S. Congress would have to re-impose them. It would be difficult getting tariffs through both chambers — including the Senate where they'd need 60 per cent support.
"It strikes me as very unlikely that you'd do it," the Toronto lawyer said in an interview.
Then there's the final hurdle: modern economic reality. Warner said businesses have become increasingly international and now build products with parts from different countries.
"You would see businesses going nuts," Warner said.
"How do you reverse those supply chains now? ... Reversing NAFTA would be like closing the barn door after everybody's gone. The changes that have been made have been made."
Trump's most ardent supporters include people struggling in the modern economy. A New York Times exit poll from New Hampshire found Trump's biggest victory margins were among voters earning less than $30,000 and those claiming they're falling behind financially.
In an interview with three Trump supporters, none complained about or even seemed aware of the earlier 1987 Canada-U.S. free-trade agreement. But they did complain about jobs going to Mexico later.
"NAFTA — that changed our country. Everyone's moving out," said Bridget Trepsas.
"Everything went out."
Warner suspects a future president who promises to fix NAFTA would probably follow Barack Obama's example: In his first presidential campaign, Obama promised to reopen NAFTA to add labour and environmental provisions.
Obama says he's kept that promise by negotiating these issues in the new, as-yet-unratified Trans-Pacific Partnership. Labour unions say the new deal doesn't go nearly far enough.
Warner said it would be difficult for the next president to reopen TPP — but a piece of cake compared to cancelling NAFTA.
Sanders and Trump both oppose the TPP, too, at least in its current form.