Top business leaders from Canada, the United States and Mexico will urge their governments to publicize their support of NAFTA, in an effort to counter calls by the Democratic presidential candidates to review the deal.

Tom D'Aquino, president of the Canadian Council of Chief Executives, said the three governments should do more than just refute critics of the North American Free Trade Agreement.

"(I want to see) strong affirmation of NAFTA, an agreement we should make it work even better, and the fact we should defend it publicly," he told Â鶹´«Ã½.

Sen. Barack Obama and Sen. Hillary Clinton have both said the U.S. should review the agreement, and have even suggested withdrawing from NAFTA altogether.

D'Aquino said Canada should take those comments as a serious threat against the deal.

"I would be misleading you if I said, 'This is just political rhetoric, let's not worry about it,'" he said.

Prime Minister Stephen Harper, U.S. President George Bush and Mexico's President Felipe Calderon are preparing to meet in New Orleans on Monday and Tuesday, for the annual trilateral summit.

Business leaders said they will release a report on the benefits of NAFTA to coincide with the meeting.

But critics of the trade agreement suggest revisiting NAFTA could actually help Canada's economic interests, noting that it's been more than a decade since the deal was drafted.

"The thing's 15 years old," said Stephen Staples of the Rideau Institute. "Maybe it's time we look at the agreement and bring in some improvements on it."

Staples said crowds of anti-NAFTA protesters will descend on New Orleans during the summit, and their views should receive as much attention as the spokespeople for big business.

"These companies have the inside track on these negotiations," he said. "They have too much inside influence and regular Canadians don't find out what's happening."

With a report by CTV's Roger Smith in Ottawa