LAS VEGAS — For all the talk about the nation’s sluggish economy, especially here in the state that leads the nation in unemployment and foreclosures, it was the explosive topic of immigration that was at the heart of the most-heated exchange of Tuesday’s debate.

In fact, you could easily argue that it was the most heated exchange of any of this election cycle’s debates so far. Add one part slumping Rick Perry, eager to turn around his recent plunge in the polls. Mix one part defensive Mitt Romney, facing relentless attacks from his rivals. Stir in a debate held in a state where more than one in four are Latino. And you’ve got a recipe for fireworks.

It all kicked off when Perry accused Romney of hiring illegal immigrants to work on the lawn of  his Massachusetts home .

“Mitt, you lose all of your standing, from my perspective, because you hired illegals in your home and you knew about it for a year,” Perry said. “And the idea that you stand here before us and [say] that you’re strong on immigration is on its face the height of hypocrisy.”

“Rick, I don’t think I’ve ever hired an illegal in my life,” responded Romney.

“We hired a lawn company to mow our lawn, and they had illegal immigrants that were working there,” said the former governor of Massachusetts. “And when that was pointed out to us, we let them go.

“So we went to the company and we said, look, you can’t have any illegals working on our property,” he said. “I’m running for office, for Pete’s sake, I can’t have illegals. It turns out that once questioned, they hired someone who had falsified their documents, had documents, and therefore we fired them.”

Afterward Romney’s staff accused Perry of  ”personal cheap shots,” in the words of senior adviser Eric Fehrnstrom.

“Mitt Romney hired a legitimate company, the company in turn hired illegal immigrants. When it was pointed out to Mitt Romney he told the company to correct the problem,” Fehrnstrom said. “When the company failed to correct the problem, he fired them.”

The fiery debate exchange was the talk of the spin room as campaign aides from all candidates addressed the touchy issue of immigration.

Rosario Marin, who supports Perry, defended the Texas governor, explaining that he was saying to Romney “Don’t attack me when you’re [part of the problem].”

J.D. Gordon, the vice-president of communications for the surging Herman Cain, said, “You know we have 50 million Latinos in the United States, so it is an important issue for all of them and for the whole country. I think it’s important to strengthen the border, but I am in favor of – and the campaign is in favor of – legal immigration.”

The issue is sure to be a key one in the upcoming elections, especially with the Latino population increasing all the time in states like Nevada. The Silver State is set to be the third to vote in January, making it especially important. The Latino population here is on the rise, up 7 percent in the past decade. In 2008, Latinos backed Barack Obama by a two-to-one margin, propeling him to a 55-43 victory here.

“Thirty percent are Latinos here, so the national campaign is going to have a real Latino effect,” said Fernando Cortes who’s with Ron Paul’s campaign. “Therefore Nevada is where we start.”

“I think [the election] is going to be very emotional because now Latinos have power when it comes to voting,” said Miguel Orozco of Newt Gingrich’s campaign.

Even before Tuesday’s debate, immigration had already played a prominent role in this election cycle, especially in the Romney-Perry battle. Perry, who has an extensive background in immigration because of his state’s massive border with Mexico, has said he does not support a fence across the border. But Romney does support one, claiming that employers in America are “magnets” to illegal immigrants seeking work and whose legality is never properly verified.

At a debate last month in Florida, Perry even went so far as to accuse Romney of “not having a heart” because the former Bay State governor said he opposed giving in-state tuition rates to illegal immigrants.

To which Romney retorted, “I think if you’re opposed to illegal immigration it doesn’t mean you don’t have a heart it means you have a heart and a brain.”

The Obama campaign contends that whether the GOP nominee is Romney or Perry or someone else, Latinos should favor the incumbent president for another term in the White House.

“The choice for Hispanic Americans is between a president who passed legislation that kept 1.9 million Latinos out of poverty, provided 150,000 additional Hispanic students with the means to go to college, and fought to pass comprehensive immigration reform and the Dream Act, and a Republican field whose leading candidates oppose the Dream Act and a path to citizenship for immigrants and would slash funding for education, Medicare and Social Security,” said Gabriela Domenzain, an Obama campaign spokeswoman.

After the fireworks in Las Vegas this week, it’s clear that the fight over immigration has already heated the election debate to a boiling point. And right now it shows no signs of cooling down.