WASHINGTON (Reuters) - President George W. Bush on Monday urged lawmakers to quickly approve the Colombia free trade agreement he was sending to the U.S. Congress, but Democratic critics said the pact was not ready for a vote and would fail.

“This agreement will advance America’s national security interests in a critical region,” Bush said. “It will strengthen a courageous ally in our hemisphere, it will help America’s economy and America’s workers at a vital time, it deserves bipartisan support from the United States Congress.”

Some in the Democratic-led Congress have objected to ratifying the agreement over concerns about violence against trade unionists in Colombia and about potential U.S. job losses.

The agreement would cut tariffs on imported goods from both countries, although many Colombian goods already enjoy duty-free entry to the United States. Proponents argue a failure to pass it would mainly hurt U.S. farmers and workers.

“While we will continue to work closely with Congress, the need for this agreement is too urgent, the stakes for our national security are too high, to allow this year to end without a vote,” Bush said before signing a letter to transmit the agreement to Congress on Tuesday.

Congress then has 90 legislative days to complete action. “Waiting any longer to send up the legislation would run the risk of Congress adjourning without the agreement ever getting voted on,” Bush said.

Key Democrats criticized Bush for seeking a vote before what they considered sufficient consultation with Congress.

“Under present circumstances, we cannot support the U.S.-Colombia Free Trade Agreement,” said House of Representatives Speaker Nancy Pelosi and House Ways and Means Committee Chairman Charles Rangel in a joint statement.

The trade deal would expand markets for U.S. products at a time of economic slowdown, when “we should be doing everything we can to open up new opportunities for growth,” Bush said.

Passing the trade pact also would shore up U.S. credibility and undercut common leftist foes of Washington and Colombian President Alvaro Uribe in Latin America, Bush said.

“By acting at this critical moment, we can show a watching world that America will honor its commitments, we can provide a powerful rebuke to dictators and demagogues in our backyard, we can expand U.S. exports and export-related jobs,” he said.

Uribe, a supporter of free markets who has clashed recently with the left-wing leaders of Venezuela and Ecuador over charges they have backed Colombian rebels, has lobbied hard for the free trade deal to be passed swiftly.

“The government of Colombia is confident that U.S. legislators from both parties will recognize the great importance that this agreement has,” Uribe’s government said in a statement released by the Colombian Embassy in Washington.

U.S. President George W. Bush signs a letter to Congress regarding the Colombian Free Trade Agreement in the Old Executive Office building of White House in Washington, April 7, 2008. Behind Bush are (L-R) Defense Secretary Robert Gates, Secretary of State Condoleezza Rice, U.S. Trade Representative Susan Schwab, Labor Secretary Elaine Chao, Director of the Office of National Drug Control Policy John Walters and Agriculture Secretary Ed Schafer. REUTERS/Jason Reed

Colombia said it had reduced homicides, kidnappings and poverty in recent years. “This is the moment when we need our allies side by side to keep building a new Colombia,” it said.

“DEAD ON ARRIVAL”

But Senate Democratic Leader Harry Reid said Bush was sending the FTA to Congress prematurely because Colombia had not addressed concerns about violence against labor unionists he said was the worst in the world despite some Uribe reforms.

“By sending up the Colombia FTA legislation under circumstances that maximize the chances it will fail, he will be adding one more mistake to his legacy and one more mess for the next President to clean up,” the Nevada Democrat said.

Maine Democratic Rep. Mike Michaud, co-founder of the House of Representatives Trade Working Group, said Bush’s effort to force a vote in the face of many Democrats’ misgivings meant “the Colombia FTA is dead on arrival.”

The push for passage of the Colombian free trade deal will begin in earnest on Tuesday, when trade unionists from the South American country will talk to U.S. lawmakers, according to House Republican Whip Roy Blunt of Missouri.

He noted that a Peru trade deal passed the U.S. House of Representatives last year with about 90 percent of Republicans voting for the measure and nearly half of the Democrats joining in. “That’s about what we would need again for this (the Colombia trade deal) to happen,” Blunt said.

The Colombia trade deal roiled the race for the U.S. Democratic presidential nomination over the weekend, when a top campaign strategist to Sen. Hillary Clinton resigned under fire for his meeting with a Colombian diplomat to discuss the pact.

Clinton said on Monday she would vote against the agreement and “urge my Senate colleagues to do the same.”