Potential Republican presidential nominees are now realizing the issue of immigration will be an important one in the upcoming 2016 General Election, ABC News reports.

Wisconsin Gov. Scott Walker, who has not yet announced officially whether he will run for president, has shifted his thoughts on immigration. In 2013, he said giving immigrants a way to become citizens "makes sense." Then, earlier this month, he said he no longer supports "amnesty."

Jeb Bush, another likely Republican presidential nominee, has shifted his opinions on immigration, Poltifact reported. He has previously held a hard-line policy that encouraged deportations of illegal immigrants. He then said he would support a path to citizenship for illegal immigrants. Again, he changed his mind with a book released in 2013 that said explicitly opposed citizenship and called giving citizenship to immigrants an "undeserving reward" for those who came her illegally. Currently, Bush says he supports a comprehensive immigration reform that includes border security, guest workers and eventual legal status for undocumented immigrants.

"The best plan, the most realistic plan, the grownup plan, once you control the border ... is to say, 'Let these folks achieve, earn legal status,'" Bush said during a recent trip to New Hampshire. "If we just keep people in the shadows, we're not going to solve our immigration problems."

Florida Sen. Marco Rubio co-wrote a bill that would give immigrants a path to citizenship. The bill passed the Senate and failed in the House. He now says the bill was the wrong approach to immigration. He says the focus on immigration should be on border security.

Kentucky Sen. Rand Paul voted against Rubio's bill but also said the millions of illegal immigrants in the country cannot all be sent home.

New Jersey Gov. Chris Christie said he once supported an overhaul to immigration but will not say where he stands now. Christie's state of New Jersey is backing other Republican states in a suit against President Barack Obama's order to prevent deportation for some immigrants.

Former Texas Gov. Rick Perry is strengthening his statements on immigration. In 2012, during his campaign, Perry called his rivals heartless if they opposed a law that gives some children of undocumented parents in-state tuition at public colleges. Perry now says the U.S. will not deport all of those here illegally.

Matt Schlapp, chairman of the American Conservative Union, said things have changed and caused these presidential hopefuls to rethink their stance on immigration. He said the large push of Central American youths crossing the border illegally last summer has overwhelmed federal officials. He also said that Obama's act to prevent deportation of some undocumented immigrants has also caused them to rethink their stances.

"You've got to cut these guys some slack," Schlapp said of the Republicans.