Bayamon, Puerto Rico ? Looking toward the critical primary in Illinois, Republican presidential front-runner Mitt Romney wrapped up a shortened campaign trip to Puerto Rico on Saturday as he prepared for more tough contests against chief rival Rick Santorum.

The former Massachusetts governor dramatically curtailed his trip to the U.S. territory, which holds its primary today, in favor of spending more time in Illinois, where polls have shown him slightly ahead of Santorum. Romney had planned to spend the weekend and visit a polling place today, but instead left the island immediately after a morning appearance.

Santorum left Puerto Rico earlier this week and spent the morning in Missouri, where he already won a primary that awarded no delegates. Missouri Republicans were meeting in county caucuses Saturday, the first step toward choosing delegates to the national convention who are committed to specific candidates. Santorum then headed to Illinois Saturday afternoon, where he went on the attack against Romney.

“If you want to know where Mitt Romney’s going to be, just watch the Weather Channel,” Santorum said in a high school gymnasium in the town of Herrin.

Romney campaigned Saturday morning with Puerto Rican Gov. Luis Fortuno, shopping for tropical fruit and meeting with voters a day after a massive, energetic rally in San Juan celebrated his arrival here.

“It was Ronald Reagan who very famously in our party said that it was important for the people of Puerto Rico to have the choice to become a state, and if the people of Puerto Rico choose that path, I will be happy to lead that effort in Washington,” Romney said after the crowd began chanting “Statehood now! Statehood now!”

The island’s political status — statehood, independence or no change — is the critical issue underlying today’s primary. Puerto Ricans will vote on the island’s status in November.

Romney has support from much of the establishment here, including Fortuno, who supports making the island the 51st state, and Romney is confident about his prospects for winning many of the island’s 20 delegates.

Santorum campaigned here earlier in the week and said he would support statehood if the November vote were decisive. Santorum also spent days explaining his comment that English would have to become the island’s main language for Puerto Rico to realize statehood. That’s an emotional issue because only a fraction of Puerto Rico’s residents speak English fluently, and many feel strongly about controlling their own cultural and linguistic identity.

Puerto Rico’s delegates will be split proportionally among the candidates, though if someone wins more than 50 percent of the vote they’ll receive all 20.

As he shopped for tropical fruit — including papayas, mangoes and clementines — Romney said he was “cautiously optimistic that we’re going to do well in Puerto Rico.”

He was less certain about Illinois.

“You know, I hope that we’re going to do well there as well. But I’m going to be there this afternoon, so we’ll see,” Romney said.

Romney wasn’t initially supposed to be in Illinois on Saturday. That was before he lost Mississippi and Alabama to rival Santorum, ratcheting up pressure for him to do well in Illinois. Romney has eked out victories over Santorum in Michigan and Ohio, two other critical Midwestern states, as he has struggled to stave off the former Pennsylvania senator’s challenge.