Any move to tear up the North American Free Trade Agreement would devastate the economies of members Canada, Mexico and the United States, the head of an influential U.S. business group said on Monday.
U.S. President Donald Trump, who says NAFTA has been a disaster for American workers, wants to renegotiate the deal and says he is prepared to walk away if he does not get the changes he wants.
Thomas Donohue, president and chief executive officer of the U.S. Chamber of Commerce, said Canada and Mexico were America's two top export markets.
"Withdrawing from NAFTA would be devastating for the workers, businesses, and economies of our countries," he told a business audience in the Canadian capital Ottawa.
"Beneath all the debates, arguments, and attention-grabbing headlines, I think our leaders across the board understand this," said Donohue, who was due to meet Canadian Prime Minister Justin Trudeau later in the day.
Canada and Mexico both send the bulk of their exports to the United States and would suffer badly if NAFTA were ripped up.
Since Trump won the election, senior Canadian officials have stressed to their U.S. counterparts how closely linked the two economies are.
Trudeau also is fond of noting that 9 million U.S. jobs rely on exports to Canada, a point that Donohue repeated.
"First, let's do no harm. Let's preserve, protect, and advance the robust trade that supports both of our economies and millions of our workers," he said.
Donohue, who did not criticize Trump, said it was crucial for the United States to keep NAFTA as a single agreement rather than negotiating bilateral deals with Canada and Mexico.
"To address areas open for modernization or improvement, we would insist on doing it in a way that doesn't disrupt the US$1.3 trillion worth of trade that depends on NAFTA," he said.
Perrin Beatty, who heads the Canadian chamber of commerce, noted that Trump had promised to boost employment.
"You don't create jobs by dismantling a relationship that works well," he told reporters after the speech.