Romney, Santorum emphasize English language while appealing to Spanish speakers in Puerto Rico

Shown here are Mitt Romney, left, and Rick Santorum. (AP)

GOP presidential candidates Mitt Romney and Rick Santorum are standing by their claims that English should be the official U.S. language while attempting to court Spanish-speaking voters in Puerto Rico ahead of Sunday's presidential caucuses.

Romney is running a 60-second radio spot in which his son Craig and Puerto Rico Gov. Luis Fortuno tout the candidate's plans to include the U.S. territory is his economic-recovery package, if elected.

"Yo soy Mitt Romney ... Muchas gracias," the former Massachusetts governor says at the close of the ad.

On Thursday, Santorum toured the English- and Spanish-speaking island and attempted to clarify recent statements on the issue, saying English should be the official language but not the "only" one spoken in the United States.

"English should be taught here, and everyone should speak English here," Santorum, a former Pennsylvania senator, said in Old San Juan. "It's not the only language in California. It's not the only language in Arizona."

GOP presidential candidate Newt Gingrich also has said English should be the official U.S. language.

Roberto de Posada, a conservative strategist and former president of the Latino Coalition, says Romney tells conservatives that English must be the official language, then says he supports statehood for Puerto Rico without any language or financial requirements.

De Posada also says that statehood would increase the size of the federal government, which goes against Romney's pledge to cut spending.

"Mitt Romney has a credibility problem among conservative voters," he said.

Romney leads Santorum and Gingrich in most polls and in the fight to get the most delegates before the GOP nominating convention in August. He also appears to be the favorite in the Puerto Rico contest, in which 23 delegates are up for grabs.

A recent Fox News Latino poll shows 70 percent of Hispanics, a key voting bloc, would vote for President Obama, compared to 14 percent for Romney in a potential matchup. The president would get 69 percent, compared to 14 percent for Santorum, and Gingrich would get 14 percent, compared to 72 percent for the president, according to the poll last month of 1,200 likely Latino votes.