SAN JUAN, Puerto Rico (AP) -- Mitt Romney scored an overwhelming win Sunday in Puerto Rico's Republican presidential primary, trouncing chief rival Rick Santorum on the Caribbean island even as the two rivals looked ahead to more competitive contests this week in Illinois and Louisiana.
The victory in the U.S. territory was so convincing that Romney, the GOP front-runner, won all 20 delegates to the national convention at stake because he got more than 50 percent of the vote. That padded his comfortable lead over Santorum in the race to amass 1,144 delegates to clinch the nomination.
Nevertheless, the GOP nomination fight is unlikely to end anytime soon, with Santorum refusing to step aside even though Romney is pulling further ahead in the delegate hunt.
As the day began, Santorum claimed he was in contest for the long haul because Romney is a weak front-runner.
"This is a primary process where somebody had a huge advantage, huge money advantage, huge advantage of establishment support and he hasn't been able to close the deal and even come close to closing the deal," Santorum said. "That tells you that there's a real flaw there."
Yet, Santorum sidestepped when asked if he would fight Romney on the convention floor if he failed before August to stop the former Massachusetts governor from getting the required number of delegates.
Romney, in turn, expressed confidence that he'd prevail.
"I can't tell you exactly how the process is going to work," Romney said. "But I bet I'm going to become the nominee."
Both are aggressively competing in the next two states to vote. Illinois, a more moderate Midwestern state, is seen as more friendly territory for Romney, while Santorum is the favorite in the more conservative Southern state of Louisiana.
Elliott reported from Washington.