WASHINGTON — Mitt Romney easily won the Puerto Rico primary Sunday, continuing his dominance in GOP contests in America's island territories.

Romney went into the vote heavily favored, and with the backing of Gov. Luis Fortuno. He had more than 82 percent of the vote when the Associated Press, citing a local election official, called him the winner Sunday evening.

That margin guarantees Romney all 20 of the delegates at stake in today's vote. Delegates would have been awarded proportionally if Romney had been held below 50 percent, a fact that drew Rick Santorum to the island this week.

That decision proved to be a tactical blunder. His campaign effort there was dominated by his statement that speaking the English language would be a condition for admitting Puerto Rico to the union as the 51st state, a point he defended Sunday.

“Only 15 percent (of the population), according to the Census, are fluent in English in Puerto Rico. And what I have said is that obviously Puerto Rico is a ... Spanish-speaking island — and they'll continue to speak Spanish, and of course that's their culture, and they have every right to do so. But what I have said is that, you know, there should be fluency in English as well as Spanish,” he said on ABC's “This Week.”

Romney has said he would support Puerto Rican statehood if that was the will of the people.

Three more delegates from Puerto Rico, representing the island's elected party leadership, can express support for one of the GOP hopefuls.

Romney had already won a combined 34 delegates from Guam, the Northern Mariana Islands, the U.S. Virgin Islands, and American Samoa. Of the other GOP hopefuls, only Ron Paul picked up a delegate from those territories, in the U.S. Virgin Islands.

Citizens of those territories cannot vote in the general election, but both parties allow them a say in the process of choosing presidential nominees.

Heading into Sunday, Romney maintained the clear delegate lead according to the Republican National Committee's official tally. Of the 1,040 delegates from the states and territories that have voted thus far, Romney has 416, Santorum has 170, Newt Gingrich has 133 and Ron Paul has 26. Another 304 delegates remain unbound, largely from caucus states.

The next major prize comes Tuesday in Illinois.