NAFTA debate within the U.S. presidential campaign is mainly rhetoric and likely won't result in any change to the agreement, the American ambassador to Canada said Wednesday.

David Wilkins made the comments during an address to the Kelowna Chamber of Commerce, an audience made up of many exporters concerned about any threat to free trade with the U.S.

The trade pact has factored heavily in the Democratic contest between rival candidates Barack Obama and Hillary Clinton, who have both suggested they would renegotiate NAFTA.

Wilkins urged the B.C. audience not to take the threat seriously.

"I was in politics for 25 years, on the ballot 13 times, so I understand political rhetoric," he said. "And that's what you're seeing right now. You're seeing political rhetoric."

Clinton and Obama are experienced legislators who know the free trade agreement is too valuable to the U.S. economy to throw away, said Wilkins.

"You may hear the rhetoric more, but I don't think you'll see legislation that will change or rescind that. It's too important to both countries, and it's been too beneficial to both countries," he said.

Wilkins said trade has tripled between the U.S. and Canada since NAFTA was signed in 1992, creating the world's largest free trade area.

Last week, Wilkins acknowledged Canada may have unwittingly interfered in the presidential campaign after a confidential Canadian diplomatic memo was leaked to news outlets. The memo outlined a conversation in which an Obama official reassured a Canadian consular official that his NAFTA threats were election rhetoric.

Subsequent reports have suggested representatives from both Obama and Clinton reassured Canadian officials the NAFTA comments shouldn't be taken seriously.

Analysts believe the scandal — dubbed NAFTA-gate — may have contributed to Obama's recent loss in Democratic primaries in Texas and Ohio.

The Canadian Embassy in Washington issued a statement saying it never meant to convey that Obama's team was taking a different position on NAFTA in public than it did in private, and apologized for any "interference" the memo may have implied.

Prime Minister Stephen Harper has promised a wide-ranging probe into the leak.