Trudeau and Trump are to meet at the White House as round four of talks to revamp the North American Free Trade Agreement get underway a few kilometres away in Arlington, V.A.
The warm words between the two leaders belied the tensions in the negotiations. A letter to Mr. Trump from 310 chambers of commerce across the country on Tuesday implored the President to "do no harm" to NAFTA.
Trump has previously mused that NAFTA might be a dead agreement if the US does not get what it wants, reflecting the oft-repeated mantra of the president's America First policy.
Trudeau's meeting with lawmakers was private.
The original free trade agreement signed between the United States and Canada in 1988 did not include Mexico.
The challenge of deciphering Donald Trump's intentions for Nafta were on full display Wednesday in Washington.
On Tuesday, Donohue also singled out a "sunset clause" that would automatically terminate NAFTA every five years unless there were fresh negotiations.
Mr Trudeau, making his second visit to the White House this year, also raised the Trump administration's recent decision to hit Canadian manufacturer Bombardier with punishing tariffs on its C Series airliner.
Trump was deeply unpopular in Mexico already.
Comments this week by the two senior ministers handling the NAFTA and Trump files for Mexico suggest a growing realization - and even acceptance - that NAFTA could be over for Mexico. In fact, he told business magazine Forbes this week that NAFTA must be "terminated". "There will always be challenges that come up that we can thoughtfully work through".
"The clear focus was that we have to send a message to all the different constituencies about how much of an error it would be to cancel NAFTA, or make a bad NAFTA", Vogel said in an interview with Reuters. "We're doing it with professionals, acting in good faith, and we'll only continue with this treaty if it's in the national interest".
Trudeau will head into his meeting with Trump after talks with the influential House of Representatives' Ways and Means committee, one of two bodies of USA lawmakers helping negotiators put forward the US positions on trade.
It was quite a change of tone from the man who once had to resign from cabinet to take the blame for Pena Nieto's ill-considered invitation for Trump to visit Mexico during his presidential campaign.
Brady cited expanded market access for US dairy farmers, stronger intellectual property protection and customs barriers as key to reaching a deal. The Trump administration is calling for an 85-percent threshold, with a 50-percent requirement for USA -specific content.
Those were the days when Mexico still believed the relationship could be salvaged.
Economy Secretary Ildefonso Guajardo is the man in charge of Mexico's NAFTA team, and he said this week that Mexico has advanced to a point where it can live without the accord.
NAFTA eliminated trade barriers between the U.S., Canada and Mexico to generate trade growth.
Mr Trump, who made trade a key part of his 2016 presidential campaign, has repeatedly criticised Canada, alleging it unfairly blocks United States dairy products and subsidises its softwood lumber industry.