Donald Trump has gone from reality television star to frontrunner for the Republican presidential nomination because of one issue – immigration.

His campaign has been defined by incendiary anti-immigration rhetoric and it has found support across America with Trump securing 46% of the delegates that have been on offer so far.

The billionaire has publicly targeted Mexicans and Muslims; and while today might be a different world, the GOP stance on immigration has not always been as extreme.

36 years ago during a primary debate between then-Republican presidential candidates Ronald Reagan and George H.W. Bush in Houston, both championed immigrants living in the United States when faced with the question: “Do you think the children of illegal aliens should be allowed to attend Texas public schools for free, or do you think their parents should pay for their education?”

Bush passionately replies to the young Texan saying: "If those people are here, I would reluctantly say they would get whatever it is, what society is giving their neighbours. But the problem has to be solved ... We're creating a whole society of really honourable, decent, family-loving people that are in violation of the law, and secondly we're exacerbating relations with Mexico.”

“The answer to your question is much more fundamental than whether they attend Houston schools, it seems to me. I don't want to see ... six- and eight-year-old kids, being made, you know, totally uneducated, and being made to feel that they're living outside the law.”

“Let's address ourselves to the fundamentals. These are good people, strong people. Part of my family is a Mexican."

Similar to Bush, Reagan favoured a pragmatic approach.

"I think the time has come that the United States and our neighbours—particularly our neighbour to the south—should have a better understanding and a better relationship than we've ever had.”

"Rather than making them, of talking about putting up a fence, why don't we work out some recognition of our mutual problems, make it possible for them to come here legally with a work permit, and then, while they're working and earning here, they pay taxes here.

“And when they want to go back they can go back, and cross. And open the border both ways, by understanding their problems.”

If Trump does become President, there would be a lot more than “talk about putting up a fence”.

One of his landmark election pledges is to “build a great, great wall” on America’s southern border costing at least $8 billion. His Republican rivals Ted Cruz and Marco Rubio have also proposed similar plans.

Border controls are not a new phenomenon, there has been greater calls ever since the 9/11 terrorist attacks, but the language has dramatically changed.

“Honourable, decent, family-loving people” have now become “people that have lots of problems” and according to Trump, “they’re bringing drugs. They’re bringing crime. They’re rapists.”

This harsh rhetoric has led to concern from both sides of the political spectrum.

Hillary Clinton, who is leading the Democratic presidential nomination, commented: "One of the most distressing aspects of this campaign has been the language of Republican candidates, particularly their front-runner, that insults, demeans, denigrates different people."

"He has cast a wide net. He started with Mexicans. He's currently on Muslims.”

Hector Barreto, head of the Small Business Administration in George W Bush’s White House, said last year: “The danger we’re facing right now is if this kind of rhetoric is not checked, if this becomes normal, if the other political candidates feel: ‘Maybe I need to talk more like Trump.’”

As he inches closer to the nomination, the danger of Trump dictating what the GOP stands for will only grow.

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