SAN JUAN, Puerto Rico -- Seizing on a rare opportunity to influence U.S. politics, Puerto Rico's Democratic Party has chosen to hold a presidential primary instead of a caucus to encourage more islanders to participate in the June 1 contest, an official said Friday.

Roberto Prats, party chairman in the U.S. territory, said the switch approved Thursday by the central committee will put pressure on Sens. Hillary Rodham Clinton and Barack Obama to campaign in the Caribbean island.

With 55 delegate votes at stake, Puerto Rico will hold one of the last primaries -- followed only by Montana and South Dakota -- and could play an influential role in a tight race.

"If Puerto Rico is going to play such a significant role, we should give the world a showcase of democracy," Prats said. "We know how to vote, we vote in masses and I think it's Puerto Rico's show time."

Puerto Ricans are U.S. citizens, but they cannot vote in the general presidential election and have no voting representation in Congress.

The island has seven superdelegates among its 62 convention votes. Three of the superdelegates are committed to Clinton, two to Obama, and two are uncommitted.

Puerto Rican politics largely revolve around the long-standing debate over what should be the island's future relationship to the U.S. mainland. Clinton may benefit from the island's close links to New York, home to many people from Puerto Rico.

Island Democrats still need national party approval for the switch to a primary, but Prats said they incorporated suggestions on a draft proposal and do not expect any objections.

Prats said the contest has long been scheduled for June 1 and he attributed erroneous reports that list June 7 as the date to a typing mistake in a document sent to the national party.