"Now is not the time to renegotiate NAFTA or walk away from NAFTA," Bush said. "Now is the time to make it work better for all our people. And now is the time to reduce trade barriers worldwide."
The summit was overshadowed by Tuesday's Pennsylvania Democratic presidential primary race between Sens. Hillary Rodham Clinton and Barack Obama, who have threatened to pull the U.S. out of NAFTA or renegotiate it to push for more protections for workers and the environment.
With fears about job security already being fanned by downturns in the economy, trade has become a key issue of the presidential election. Bush argued that NAFTA has fostered prosperity in all three countries and that Clinton and Obama are wrongly using anti-trade messages to lure working class voters. Free-trade opponents say expanded international trade helps businesses, but threatens U.S. jobs and keeps wages from growing.
Bush warned that without NAFTA, migratory pressure from Mexico would be worse.
"If you do away with NAFTA, there's going to be a lot of Mexicans, more Mexicans out of work," Bush said. "It will make it harder on the border.
"So people who say, `Let's get rid of NAFTA' because of a throwaway political line, must understand this has been good for America and it's also been good for Mexico and Canada."
Bush said he was less worried about the future of NAFTA than the pending trade deals he wants Congress to ratify with South Korea, Panama and Colombia. Bush singled out House Speaker Nancy Pelosi, D-Calif., saying if she doesn't schedule a vote on Colombia she will have to take responsibility for killing the deal.
Not only will Pelosi have turned her back on a U.S. ally, Bush said, she will fuel anti-U.S. sentiment in Latin America and embolden leftist leaders like Venezuela's Hugo Chavez.
"She's going to have to explain why the voices of false populism have been strengthened, why anti-Americanism could flourish," the president said, "when America turns its back on a strong leader" like Colombian President Alvaro Uribe.
In Washington, Pelosi accused Bush of taking a partisan potshot.
She said the United States must address its own economic weaknesses before signing any more trade pacts abroad.
"Democrats stand ready to work with the president to bring the Colombia Free Trade Agreement to a vote in the House, but the timing has to be that of America's working families, not the timing of the president," she said in response.
Asked about the state of the U.S. economy, Bush said: "We're not in a recession. We are in a slowdown."
"I'm obviously concerned for our consumers," the president said. He was asked whether the rising cost of gasoline will erode the potential positive impact of the $168 billion economic stimulus package passed by Congress, but he did not answer specifically.
"No question that rising gasoline prices are like a tax on our working people," Bush said.
Bush said he chose to host his final North American summit in New Orleans to showcase the city's rebirth from the devastating effects of Hurricane Katrina in 2005. Calderon, who will host the next summit in Mexico, said NAFTA should be strengthened, not canceled. He implored Congress to ratify the Colombian trade pact.
"It's extremely important, I think, to bear in mind that when you provide more opportunities for trade in the Latin American region, there will be many more opportunities for prosperity," said Calderon, who also warned of heightened migratory pressure from Mexico if NAFTA was dissolved. "It needs to be made very clear that the prosperity of Latin America, particularly that of Mexico, is a crucial factor for the prosperity of the people of North America."
Harper said he was confident that Bush's successor would come to understand the importance of NAFTA and the commercial relationships in North America.
"I think that a rejection of or turning our backs to such as ally as Colombia could create log-term problems for our countries in South America," Harper said.
Besides trade, the three leaders talked about food and product safety standards, harmonizing auto production standards, emergency response, combatting trade of counterfeit and pirated goods, fighting organized crime, low-carbon energy, intellectual property rights, global warming and reducing bottlenecks and congestion at border crossings, such as Detroit-Windsor and San Diego-Tijuana.