By Doug Palmer 

WASHINGTON (Reuters) - Democrats will vote on a free trade agreement with Colombia only after the White House and Congress address urgent domestic economic concerns, House of Representatives Speaker Nancy Pelosi said on Monday.

"We still believe it is possible to bring the Colombia free trade agreement to the floor under the proper circumstances, but first we need to address the worsening economy," Pelosi told reporters.

Earlier, President George W. Bush said the pact was "dead" until Pelosi scheduled a vote.

"This has to be done in recognition not only of the concerns that we have about human rights violations of workers in Colombia, but based on the economic security of America's workers here in our country," the California Democrat said.

"We ask the president to, once again, bring his people to the table so we can move forward," she said.

Administration officials said they have been trying for months to engage Pelosi in talks on bringing the pact to the floor for a vote, only to have their efforts ignored.

They accuse Democrats of holding up the agreement to appease labor unions, which strongly oppose it, at the expense of other workers and the economy as a whole.

"The American worker and our foreign policy shouldn't be held hostage to Democratic Party politics, and our economy will not be better off for killing trade deals," White House spokesman Tony Fratto said.

Also on Monday, a group of prominent Democrats including several who served under former President Bill Clinton, urged Congress to approve the pact.

"We believe this agreement is in both our vital national security and economic interests," they said.

The group included former Agriculture Secretary Dan Glickman, former White House Chief of Staff Thomas "Mack" McLarty and former House Foreign Affairs Committee Chairman Lee Hamilton. Former Defense Secretary William Cohen, a Republican who served under Clinton, also signed the letter.

Clinton has supported the deal, differing from his wife, Hillary Clinton and fellow Democratic presidential candidate Barack Obama, who both oppose it.

UNION OPPOSITION

U.S. labor groups, a key Democratic Party constituency, say Congress should not vote on the pact because the Colombian government has not done enough to stop killings of trade unionists and bring their murderers to Justice.

The administration says Colombian President Alvaro Uribe has made great strides in reducing violence over the past five years, and approving the free trade pact would help his government do even more.

Pelosi did not take questions at her news conference, and gave no precise timetable for a vote on the pact.

However, she made clear it took a back seat to legislation to help Americans cope with current economic woes, such as rising food, gasoline, health care, education and other costs and that have cut consumer purchasing power.

Last week, the House of Representatives voted to indefinitely delay action on the trade pact, rather than abide by longstanding "fast-track" trade law provisions that require Congress to approve or reject trade deals within 90 days.

Bush earlier on Monday said House Democrats had "stiffed" a crucial ally by voting to indefinitely delay the pact.

Pelosi turned the criticism back on Bush.

"For seven long years the president's failed economic plan has stiffed the American people," she said.

Pelosi said Democrats see Colombia as a friend and she had extended her "good wishes" to Uribe after last week's vote.