Arcane election rules prevent residents of the island of Puerto Rico from casting a ballot in the November presidential election, but they are able to take part in party primaries.

As results came in, early indications showed Rubio taking a strong lead over fellow Republican presidential hopefuls Donald Trump and Ted Cruz. It's Rubio's second victory after winning the midwestern state of Minnesota.

Edwin Mundo, electoral commissioner for Puerto Rico's Republican Party, estimated that more than 30,000 people voted Sunday, just a fraction of the people who voted in 2012, due to a sharp reduction in the number of polling stations caused by deep budget cuts.

A decisive victory - at least more than half the vote - would hand a candidate all 20 delegates. Otherwise, they are distributed proportionally, though a candidate would have to get at least 20 percent to qualify. Three other super-delegates - elected officials and party functionaries - have already declared their support for Rubio.

Puerto Rico's political status remains controversial

The political status of the island - seized by the US in the Spanish-American War at the end of the 19th century - has been a smoldering issue for more than a century. Many Puerto Ricans - all US citizens - want full statehood for the territory and the issue remains on voters' minds.

"We have to send a message of what Puerto Rico wants, of our problems, of the help we need for the economy, and more than anything, the Republican Party here wants statehood," said Zoraida Fonalledas, the national committeewoman for Puerto Rico's Republican Party and one of the super-delegates pledged to Rubio.

Rubio has emerged as a frontrunner among establishment Republicans seeking to prevent a Trump nomination. Traditional party members have blanched at the outspoken reality TV star's calls to build a wall on the Mexican border, round up and deport 11 million immigrants who are in the country illegally and temporarily bar all Muslims from entering the United States.

Those types of remarks have brought unwanted attention to the party. German Economy Minister Sigmar Gabriel told the Welt am Sonntag newspaper that Trump was "not only a threat to peace and social cohesion, but also to economic development."

However, Republican leaders are not that much happier with Cruz, a senator from Texas, who has alienated many of his own party. This is due, in part, to remarks in which he called for the United States to "carpet bomb" the so-called "Islamic State" militant group and pledged to eliminate the federal tax collecting agency, the Internal Revenue Service.

jar/lw (AP, Reuters)