By Alec MacGillis

SAN JUAN, P.R. -- Hillary Clinton is heavily favored to win next weekend's Puerto Rica primary, but for one afternoon at least, Barack Obama today owned Old San Juan.

Puerto Rican police and Secret Service blocked off the lovely stucco-lined streets and squares high above the seaside battlements of the island's original Spanish settlement so that Obama could lead supporters in a "caminata," the traditional parade held by candidates running for office. With the Caribbean gleaming before him, Obama stepped up on a stone wall to greeted hundreds of assembled supporters and gawkers who'd waited their turn to make it through the metal detectors set up around the old town's perimeter.

"Hola, Puerto Rico! How's everybody doing today?" he shouted. He recounted his meeting earlier in the day with some Puerto Rican war veterans at a local university, said that the goals of his candicacy applied equally to the island the mainland, and pledged that as president he would do everything he could to allow Puerto Ricans to decide the future status of their island, which has been mired in a commonwealth vs. statehouse vs. independence debate for years. And he encouraged all to vote on June 1. "If we do well in Puerto Rico, there is no reason I will not be announcing that I am the Democratic nominee for president of the United States of America!"

A few moments later, he was off, walking slowly up the main drag above the fort walls in a scene of barely controlled chaos as hundreds of supporters danced behind him. (Among them were some familiar names: members of the Service Employees International Union and the Teamsters, or as they are called here, Los Tronquistas.) Others reached to shake his hand from behind barriers along the sidewalk. Island and national media shot video from a slow-moving truck and rushed ahead of him on foot as the ample, and highly anxious, security forces shouted for all to keep moving. Over it all, a sound truck blared a jouncy song written in the candidate's honor: "Obama la esperanza y el futuro...Un amigo presidente porque respeta nuestra gente." ("Obama the hope and the future/A friend president because he respects our people.")

Nearing the end of the short route, Obama broke into a few dance steps, driving the crowd even crazier. "This was a great caminata," he declared at the end. "We have great support here in Puerto Rico. The most important support is not the support from the elected officials or support from the powerful, it's the support from the people, and that is what we have shown here today."

And then he was off in the black SUVs, leaving the dazed and sun-baked supporters and reporters in his wake. One resident, Julia Delgado, said she would definitely vote for Obama next week, because she thought he was most likely to bring about the stronger economy that would allow the island to develop more on its own and grow less dependent on the mainland, without necessarily declaring full independence.

But the 54-year-old substance abuse counselor was not so impressed with the caminata, as high-spirited as it was. A real caminata, she noted, goes much longer than a few blocks. "A caminata in Puerto Rico goes everywhere," she said. "There's too much security here. What do they think we are, terrorists?"