President Obama will welcome a bruised American ally to the White House on Thursday and take a step toward mending relations. For the past decade, Colombia has been a strong and steady U.S. friend at a time when leftist demagogues — including the presidents of two of its neighbors — have dedicated themselves to turning Latin America against the United States. Colombia’s reward was to be vilified by labor unions intent on torpedoing the free-trade agreement that it negotiated with the Bush administration and that has been neglected by Mr. Obama, who skipped Colombia during his recent tour of the region.

Mr. Obama’s agreement with Colombian President Juan Manuel Santos on an “action plan” for obtaining congressional ratification of the free-trade agreement could augur both a political and a foreign policy breakthrough for his administration. Mr. Obama, who will endorse the deal just days after launching his reelection campaign, gets points for political bravery: Though Colombia made substantial concessions to win the White House’s support, the pact will still be opposed by most unions and many Democratic members of Congress.

The deal could also arrest a drift away from the United States by Mr. Santos, a moderate democratic leader elected last year who, in frustration with Washington, has been exploring deals with China and working to mend relations with Venezuela’s Hugo Chavez. (Colombia already has free-trade agreements with Canada and the European Union.) The plan Mr. Santos agreed to commits his government to new steps to protect labor leaders, the hiring of more prosecutors to pursue crimes against union members, and legal reforms to strengthen the union movement.

Mr. Obama pledged to submit the free-trade deal to Congress once Colombia completed the first reform steps; officials say that the administration will also move forward with a stalled free-trade agreement with Panama once that country’s Congress finishes passing new labor and tax laws. But the timing is not clear. Trade representative Ron Kirk says that he hopes to work out an agreement with Congress on a number of measures, including a free-trade agreement with South Korea, the renewal of a trade protection assistance program for workers, and trade preferences for Andean countries and Russia. Several of those measures have been held up by Republicans in an attempt to force action on Colombia and Panama.

If and when the Colombia treaty is approved, U.S. sales to the country may increase by $1 billion annually — a tiny step toward Mr. Obama’s goal of doubling U.S. exports by 2015. But the political benefits will be far more significant. Mr. Obama will send a message that the United States is serious about forging closer partnerships with Latin America’s rapidly growing economies; he will end a debate that for five years has bedeviled relations with a close ally; and he will show that his administration can make real progress on trade. The sooner the action plan with Colombia can be implemented, the better.

###