Immigration came up frequently during the first Republican debate - in fact during the airing of the debate on Fox News, Google Trends data showed that immigration was its fourth most-searched GOP debate issue.
On stage Wisconsin Gov. Scott Walker defended his shift in immigration views, saying he no longer supports a pathway to citizenship because he "actually listened to the American people."
He laid out his own immigration policy proposals, saying he would "secure the border, enforce the law, no amnesty, and go forward with a legal immigration system that gives priority to American working families and wages."
Florida Sen. Marco Rubio claimed that "the evidence is now clear that the majority of people coming across the border are not from Mexico. They're coming from Guatemala, El Salvador, Honduras."
In fact, 3.5 percent of people living in the United States are unauthorized immigrants, and about fifty-two percent of that population come from Mexico, according to the Pew Research Center.
Former Florida Gov. Jeb Bush also defended his earlier comments from last year when he called illegal immigration an "act of love."
"I believe that the great majority of people coming here illegally have no other option. They want to provide for their family. But we need to control our border," he said.
Then Donald Trump is now used to defending his comments about Mexican immigrants being rapists and criminals, and the topic came up again when moderator Chris Wallace asked him for evidence that the Mexican government is responsible for sending such immigrants to the U.S.
"Border patrol. I was at the border last week. Border patrol people that I deal with, that I talk to, they say this is what's happening because our leaders are stupid, our politicians are stupid, and the Mexican government is much smarter...they send the bad ones over because they don't want to take care of them," Trump said. "That's what's happening, whether you like it or not."
But his assertion about the criminality of Mexican immigrants coming to the U.S. is at odds with the findings of a 2010 American Community Survey (ACS), which found that immigrants are less likely than the native-born to be incarcerated.
According to the Pew Research Center, unauthorized immigration has remained stable over the past five years. In 2014, there were 11.3 million unauthorized immigrants living in the United States.