With a combination of attacks on President Obama and each other -- and with the Florida primary looming on Tuesday -- the four remaining candidates for the Republican presidential nomination made their case on a wide range of issues Thursday night before a receptive audience at the University of North Florida in Jacksonville.

Former Gov. Mitt Romney of Massachusetts and former U.S. House Speaker Newt Gingrich exchanged barbs throughout the debate -- but each received heavy fire from former U.S. Sen. Rick Santorum of Pennsylvania, who argued that both of them were too close to Obama on issues such as health care and energy policies.

The stakes were high. Romney currently leads in most polls of Florida, with Gingrich in second and Santorum in third. U.S. Rep. Ron Paul of Texas, who is downplaying Florida, stands in fourth.

The debate -- the 19th of the campaign cycle and the last one before the Florida primary -- was moderated by Wolf Blitzer and carried on CNN in partnership with the Republican Party of Florida and the Hispanic Leadership Network.

IMMIGRATION

The debate started with a question from the audience on illegal immigration -- with Blitzer asking the candidates about Romney’s comment about “self-deportation” in the Tampa debate on Monday.

“We need to enforce the law at the border, secure the border," Santorum said, calling for a crackdown on businesses that hire illegal aliens and pushing for a greater use of the E-Verify system.

Gingrich also called for “much stronger employee penalties” and a crackdown on illegal immigration, including using private-sector companies which, he suggested, are better in fighting fraud than the federal government. Gingrich also called for “citizen panels” to weigh in on illegal immigrants who will not leave voluntarily.

Romney said he backed greater penalties for businesses that hire illegal aliens and said his "self-deportation” idea would work.

Paul called for pulling money sent abroad to secure the border with Mexico.

“The way we’re handling our border hurts our economy,” Paul said. “We don’t have a well-managed border.”

Asked by Blitzer if he thought that Romney was the most anti-immigrant candidate, Gingrich said yes.

“That’s inexcusable,” Romney fired back, noting his father was born in Mexico and stressing that U.S. Sen. Marco Rubio, R-Fla., had defended his record. “The idea that I’m anti-immigrant is repulsive.”

Gingrich and Romney continued to spar over immigration, with Romney insisting he is for legal immigration. Santorum and Paul sat on the sidelines as the two front-runners clashed -- including over a Romney campaign ad slamming Gingrich on the issue. Gingrich insisted his plan would help elderly illegal immigrants spend their final years with dignity.

“Our problem is not 11 million grandmothers,” Romney replied.

Gingrich stressed he supports English as the official language of the government. 

“Every young American should learn English,” he said, insisting it would help them find jobs and become successes in America.

Romney said he backed “English immersion in schools” and supported it becoming the national language.

LATIN AMERICA

The debate then turned toward Latin American affairs and America’s relationship with nations in that region.

Paul called for increased free trade between the United States and Central and South American countries, including Cuba.

Santorum said he opposed Paul’s position on Cuba and took aim at Obama’s policies in that region

“Our policies in Central and South America under this administration have been abysmal,” Santorum said, accusing Obama of “siding with the leftists, siding with the Marxists.” Santorum specifically cited Obama’s reaction to the 2009 ouster of former Honduran President Manuel Zelaya, an ally of Venezuelan strongman Hugo Chavez.