CLEVELAND (CBSNewYork/AP) — As the top polling Republicans vying for the 2016 presidential nomination went head to head Thursday night, immigration policy was front and center.

Top polling candidate Donald Trump refused to back down from previous allegations that Mexico is sending criminals into the United States, though he skirted the challenge to provide evidence of that charge during the debate.

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Trump snapped back that if it weren’t for him, no one would be talking about illegal immigration.

The real estate mogul said U.S. Border Patrol agents told him the Mexican government is sending criminals to the U.S. because they know the government in America is “stupid.”

“They say this is what’s happening because our leaders are stupid, our politicians are stupid. And the Mexican government is much smarter, much sharper, much more cunning,” Trump said.

Ohio Gov. John Kasich said that Trump’s immigration comments have clearly touched a nerve and it is “a mistake” for people to ignore him.

Meanwhile, Florida Sen. Marco Rubio said Thursday night many U.S. citizens feel taken advantage of when it comes to immigration.

“This is the most generous country in the world when it comes to immigration,” he said.

Rubio also fired back at Trump’s assertion that Mexico is to blame for America’s illegal immigration problem.

According to the senator, illegal immigrants are coming from countries such as Guatemala and El Salvador and are overstaying their welcome, as opposed to sneaking over the border.

Former Florida Gov. Jeb Bush defended his statement last year that people in this country illegally have committed “an act of love.”

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Bush said most people staying in the country illegally are trying to provide for their family, a position that earned him groans from the audience.

Bush argued that fixing the immigration system is more important than figuring out why people are in the country illegally, and called for legal immigration based on family ties, and expanding it for economic reasons.

“There’s much to do. Rather than talking about this as a wedge issue, the next president will fix this once and for all, as a driver for high, sustained economic growth,” he said.

Fox News anchor Megyn Kelly also grilled Trump with a pointed question referring to prior comments he’d made about women.

“You’ve called women you don’t like, ‘fat pigs,’ dogs, slobs, and disgusting animals,” she asked Trump. “Your Twitter account has several disparaging comments about women’s looks. You once told a contestant on ‘Celebrity Apprentice’ it would be a pretty picture to see her on her knees. Does that sound to you like the temperament of a man we should elect as president?”

Trump quickly tried to make light of the question by telling Kelly, “Only Rosie O’Donnell.”

But when Kelly pressed back that the comments went “beyond Rosie O’Donnell,” Trump defended his brash modus operandi.

“The big problem this country has is being politically correct. I’ve been challenged by so many people and I don’t frankly have time for total political correctness. And to be honest with you, this country doesn’t have time either,” he said. ” Frankly what I say and oftentimes it’s fun, it’s kidding, we have a good time. What I say is what I say. And honestly, Megyn if you don’t like it, I’m sorry.”

O’Donnell later issued her own response on Twitter: “Try explaining that 2 ur kids.”

O’Donnell and Trump have a rocky history. Back in 2011, the pair launched a Twitter feud, sparked by Trump’s comments about O’Donnell’s engagement to partner Michelle Rounds.

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