Mitt Romney handily won Puerto Rico's primary on Sunday, trouncing challenger Rick Santorum in his quest to try and create the mathematical inevitability to score the Republican presidential nomination to challenge President Obama.

Romney, the GOP front-runner, picked up all of Puerto Rico's 20 delegates because he got more than 50 percent of the vote. About 150,000 people were expected to cast ballots.

The win further boosted Romney's delegate lead over his rivals. Romney now has 521 delegates, while Santorum has 253, Newt Gingrich 136 and Ron Paul 50.

Romney aide Eric Fehrnstrom tweeted a tweak at Santorum, saying that he suffered a "huge loss" in Puerto Rico. Gingrich and Paul did not compete in the contest.

While Santorum and Romney campaigned on the island territory last week, they are also looking forward to Tuesday's primary in Illinois, with 69 delegates and then to Louisiana on the weekend, which provides 18 pledged delegates.

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The goal is an algebraic equation that forces one of two scenarios: Romney begins to wrap up his quest for the 1,144 delegate majority needed for victory, or Santorum, with the help of Gingrich's proportional take, pulls away enough delegates from the front-runner to halt him in his tracks and possibly force a brokered convention.

At that rate, Romney is on pace to capture the nomination in June unless Santorum or Gingrich is able to win decisively in the coming contests.

"I know a lot of people will talk about delegates and strategies and math and that's all very interesting to the insiders. But I think the American people want to see someone who has the leadership, skill and experience to beat the president," Romney told "Fox News Sunday."

"I can't tell you exactly how the process is going to work. But I bet I'm going to become the nominee," Romney said.

Santorum, however, rejects the notion that Romney can run away with it.

"We still believe that there are plenty of delegates out there for us to do what we have been doing, which is actually going out there and winning states and winning the tough battles, and doing so over pretty overwhelming odds," Santorum told ABC's "This Week" on Sunday.

He added that he also rejects the notion that the GOP candidate is doomed against President Obama if the nominee is not chosen until the late August convention to be held in Tampa.

Offering a critical take of his rival, Santorum said the primary has given him a chance to bone up against the president in a general election contest.

"I feel like I'm doing a training run for the general election. The same issues I'm out there campaigning on against Governor Romney are the same issues I'm going to campaign against Barack Obama on," Santorum said. "Unfortunately, Governor Romney and Barack Obama are in the same place."

Romney, who has expressed confidence about his prospects for winning many of Puerto Rico's delegates, has support from much of the island's establishment, including its governor, Luis Fortuno, who supports making the island the 51st state. Fortuno and Romney spoke after the victory was declared, Romney's campaign tweeted.

Santorum has tried to blunt, if not negate, a potential victory. He left last week to go to Puerto Rico, which participates in the nominating process, but as a territory rather than a state, doesn't have a vote in the general election.

Santorum has said he would support statehood if the November vote were decisive. He also has spent days explaining his comment that English would have to become the island's main language for Puerto Rico to realize statehood. Only a fraction of Puerto Rico's residents speak English fluently.

Illinois also provides an interesting test. Its largely considered a northern state, with the kind of suburban, upscale voters that Romney has done well with in earlier primaries. However, downstate, it has a significant rural population and borders Iowa and Missouri, where Santorum has done well.

Romney is maintaining his lead in most polls, but it's a lead that has been narrowed in recent days with Santorum gaining a bit of momentum. Romney curtailed his trip to the U.S. territory Saturday in favor of spending more time in Illinois, where he campaigned on Sunday.

The candidates have until the last primary in Utah on June 26 to score the 1,144 delegate majority. If not, the GOP would host their first convention floor fight since 1976.

But most analysts discount the likelihood of a brokered convention or a floor flight at the convention despite Democrats' obvious amusement at such a possibility.

"We thought we'd have a nominee by now. But, you know, every time it looks like Mr. Romney has some momentum, he gets set back. He hasn't been able to make the sale to his own party," said Obama's chief campaign adviser David Axelrod.

"I think the Republican Party is having a hard time picking a nominee," Axelrod said, adding that "if he thinks he's an economic heavyweight, he must be looking in a funhouse mirror, because that is not the record of an economic heavyweight."

"I think David's living in a permanent funhouse mirror myself," responded Republican National Committee Chairman Reince Priebus, who followed Axelrod on CBS' "Meet the Press."

"We're not making plans right now for a brokered convention. But the up side is that we've got rules to handle any possibility. And obviously, we're going to follow those rules. But right now what we're talking about is how who is going to be our nominee and what this president promised to the American people and what he delivered," Priebus said.

Fox News' Doug McKelway and The Associated Press contributed to this report.