MEDELLIN, Colombia (Reuters) - The United States would break faith with a strong Latin American ally that has rescued itself from failure if the U.S. Congress refuses to approve a free-trade agreement with Colombia, Secretary of State Condoleezza Rice said on Thursday.

"I think it would be ... a very bad signal for the people of Colombia -- not to mention the people of the region -- that you do difficult things, you work hard, you bring your country back from the brink and the United States doesn't deliver," Rice told reporters before arriving in Medellin.

She was traveling with a delegation of nine Democratic U.S. legislators whom she hopes to persuade to vote in favor of the trade accord.

While Colombia needs to improve its human rights record, Congress should recognize the progress President Alvaro Uribe has already made toward ending decades of civil conflict and demobilizing paramilitary forces responsible for most of the past abuses, Rice said.

"It's very obvious that just a few years ago I think you could have said that Colombia was in danger of being a failed state. And it's come back from that," she said.

Rice's trip is one of several senior Bush administration officials are leading over the next two months to build support for the Colombia agreement.

Despite the administration's push, the AFL-CIO -- the largest U.S. labor group and a key Democratic party supporter, strongly opposes the free-trade deal.

House of Representatives Speaker Nancy Pelosi and other senior Democrats said last June that Colombia needed to make much more progress to reduce violence against trade unionists and punish murderers before Congress would vote on the pact.