Washington: Frontrunner Mitt Romney has won the Puerto Rico's Republican presidential primary, taking him a step closer to bagging party's nomination to challenge incumbent Barack Obama in the fall.

Mainstream American media declared him the winner on Sunday as early results showed that he had more than 80 percent of the votes polled.

Rick Santorum, the former Pennsylvania Senator, was a distant second with less than 10 percent of the votes, while Newt Gingrich, former Speaker, US House of Representatives, had just three percent of the votes.

At a time, when every delegate is expected to count, given that all the three major contestants are yet to reach the magic figure of 1,144 – necessary to bag the party's nomination – Romney is expected to get all the 20 delegates at stake from the Puerto Rico primary.

This adds another milestone to Romney's presidential aspirations as the Puerto Rico win helped him cross the 500 delegate mark. He is ahead of the delegate counts of both Santorum and Gingrich taken together.

However, US media said Romney still has a long way to go to bag the party's nomination. "Romney's win in Puerto Rico gives him a small boost heading into next Tuesday's pivotal Midwestern primary in Illinois, and Saturday's Louisiana contest," as reported.

"As primaries go, Puerto Rico's is not the most critical. There were only 100,000 registered Republicans in the state as of the 2000 election; the primary was open to all voters. Residents cannot vote in the general election. But in what's becoming a delegate race between Romney and Santorum, every little bit counts," as reported.

"As the Republican race deepens into a fight for every delegate, the Romney campaign pointed to Puerto Rico as the latest sign of strength over Rick Santorum. Romney was defeating Santorum by a wide margin in the United States territory, which has 20 delegates. Romney was likely to take all of them," as reported.