WASHINGTON (Reuters) - President George W. Bush criticized Democratic presidential candidates on Thursday for suggesting the United States could "opt out" of the North American Free Trade Agreement and urged Congress to boost U.S. exports by approving a trade deal with Colombia.

"There are a lot of farmers and businesses, large and small, who are benefiting from having a market in our neighborhood. And the idea of just unilaterally withdrawing from a trade treaty because of, you know, trying to score political points is not good policy," Bush said during a White House press conference.

During a presidential campaign debate earlier this week in Ohio, both Democratic Sens. Hillary Clinton and Barack Obama criticized NAFTA and said the United States could opt out of the agreement if Mexico and Canada don't agree to renegotiate labor, environmental and investment provisions of the pact.

The candidates were responding to the strong view of many Ohio voters that the 14-year-old agreement is responsible for many manufacturing job losses in that state, which holds a crucial presidential voting contest on Tuesday.

Bush warned withdrawing from the pact would hurt U.S. farmers and businesses who export around $380 billion worth of goods to Canada and Mexico each year and said a signal that the United States does not honor its trade commitments.

Canadian and Mexican official have also expressed alarm at the idea of renegotiating the pact.

"It would be like throwing a monkey wrench into the engine of North American competitiveness," Arturo Sarukhan, Mexico's ambassador to the United States, told the Financial Times in a story published on Thursday.

Bush also warned that congressional rejection of an unpopular free trade pact with Colombia would damage U.S. national security interests in the Latin American region and said he expected lawmakers to vote on the pact soon.

"The Colombia free trade vote is coming up," Bush said.

Colombia currently receives duty-free treatment for most of its goods under a U.S. trade preference programs that dates back to the early 1990s.

The pending trade deal would lock in that duty-free access and phase out Colombia's tariffs on U.S. exports.

Congressional Democrats have said Colombia needs to make more progress in reducing violence against trade unionists and putting murderers in jail before they can support the pact.

Both Obama and Clinton also oppose voting on the Colombia agreement at this time.

(Reporting by Doug Palmer, Editing by David Wiessler)