Donald Trump could well decide to cancel NAFTA, former prime minister Stephen Harper warned Wednesday as he ended his public silence on current events by describing anti-trade sentiment in the U.S. as an intractable, long-term problem with no easy fix.

Harper stepped into the role of political analyst during a panel discussion in Washington, a coincidence of timing that bordered on the surreal: at the very same moment, Harper's successor Prime Minister Justin Trudeau was a few blocks away at the White House, discussing the North American Free Trade Agreement with the U.S. president himself.

Powerful anti-trade forces that predate Trump's presidency are at play in American society and aren't going away anytime soon, said the former Conservative leader, who's known as an ardent free trader.

He recalled being told by the Bush administration when he took office in 2006 that NAFTA would never have won a vote in the U.S. Congress at the time. He described how Barack Obama campaigned against the deal. He believes trade will remain controversial, whether or not Trump cancels NAFTA, which he thinks could happen.

Harper said he is advising companies to start planning for the possibility of a world without NAFTA.

"I believe that it is conceivable. I believe Donald Trump would be willing to take the economic and political risk of that under certain circumstances," Harper said in a panel at the Dentons law firm.

"I would not want to simply bet that this is just all going to work out. What's driving this are some very powerful political currents that, frankly, nobody — including Mr. Trump — has really figured out how to address, and they're going to keep coming at us."

Free trade frustration

Trudeau, for his part, sounded Wednesday like he was coming around to a similar conclusion.

"I continue to believe in NAFTA; I continue to believe that as a continent working together in complementary ways is better for our citizens and better for economic growth, and allows us to compete on a stronger footing with the global economy," Trudeau told a news conference.

"So saying, we are ready for anything and we will continue to work diligently to protect Canadian interests, to stand up for jobs, and look for opportunities for Canadian business and citizens of all of our friends and neighbour countries to do well."

Harper said he doesn't believe a simple fix to NAFTA, with a few tweaks, will satisfy the unpredictable Trump, who has repeatedly blasted the trade deal as bad for the U.S., and has a political need to show he's achieved important changes: "I just don't know how you get from here to there."

Harper said he understands anti-trade frustration.

He described his own annoyance at spending his 50th birthday signing a bailout package for General Motors Canada, only to see the auto giant later move jobs out of the country.

"I'm not your average assembly-line worker, but even I was irritated by that."

Former prime minister Stephen Harper revisits his regrets, frustrations and irritations with the 2009 auto bailout. 0:49

And while he proudly touts the fact that he signed trade agreements with dozens of countries, he not only sympathizes with people who feel they've been left behind by the modern economy — he agrees with them. Harper said they can't blame Canada, or even Mexico, or possibly even trade deals — but there can be little doubt jobs have moved away, especially to China.

"I've looked at the data," Harper said. "These people do not (just) perceive they have been left behind. They actually have been left behind... It's a reality."

He said he wanted to avoid opining too much on current politics, so he declined to discuss possible solutions to these problems. He also declined an interview request. He offered one piece of advice, albeit in vague terms: He urged other parties to try seeing the issue through the U.S. government's eyes, and finding solutions it can sell.

Another panellist was slightly more optimistic.

No end to NAFTA: Gingrich

Newt Gingrich — a fixture of American politics and friend of the president — suggested Trump doesn't really want to end NAFTA. He said he thinks a deal can eventually be reached, after long and difficult negotiations.

"My hunch is in the end we will get to a reformed NAFTA. We will not get to the end of NAFTA," said the former House speaker and Trump campaign surrogate.

"I don't think there's an appetite for blowing it all up, other than the president's occasional tweets... I think it"ll be a brawl (though)." He suggested the deal might get a new name: "It will probably be something like the Modernized Dramatically Improved 21st Century Trumpized NAFTA."

Gingrich prefaced his remarks by saying the president is unpredictable, so nobody knows for sure.

Harper, meanwhile, also offered opinions on two other international relationships. He said Canada could easily strike a trade agreement with a pro-Brexit British government. He also said that if NAFTA collapses, the Chinese will be ready and willing to make a deal with Canada.