Donald Trump and other GOP candidates want to radically change a 150-year-old cornerstone of American citizenship

When the famous immigration hawk US Rep. Steve King (R-Iowa) proposed a bill to end so-called "birthright citizenship," just 27 far-right Republican members of the House of Representatives signed on as cosponsors.

The bill, and the issue, got little traction, however. Seven months later, enter Republican presidential front-runner Donald Trump.

Since the real-estate magnate unveiled his official immigration-reform plan last month, at least four Republican candidates have followed him on one of his more controversial proposals: ending birthright citizenship, the constitutional right that automatically grants American citizenship to anyone born in the United States.

"Donald Trump has provided the opening," said Dan Stein, president of the Federation for American Immigration Reform.

Despite being written off by pundits and political observers as an unserious candidate with little chance at winning the presidency, Trump is undoubtedly helping to set the agenda for Republican candidates. And he has continually brought one issue in particular into the spotlight: immigration.

The spotlight once again shone on immigration during the second Republican presidential debate Wednesday night.

Trump's immigration proposal, crafted with the help of one of the most conservative members of the US Senate, is full of red meat that has until this point been largely advocated by anti-illegal-immigration groups - not presidential candidates.

Perhaps the most radical change in the plan, however, is the one aimed at ending the concept of birthright citizenship - overturning a key concept of the 14th Amendment to the US Constitution. That issue was again thrown into the discussion loop Wednesday night, during the second Republican presidential debate on CNN.

"A woman gets pregnant. She's nine months, she walks across the border, she has the baby in the United States, and we take care of the baby for 85 years. I don't think so," Trump said during the debate.

"And by the way, Mexico and almost every other country anywhere in the world doesn't have that. We're the only ones dumb enough, stupid enough to have it. And people - and by the way, this is not just with respect to Mexico. They are coming from Asia to have babies here, and all of a sudden, we have to take care of the babies for the life of the baby."

Even some of Trump's most frequent sparring partners in the Republican field, like Sen. Rand Paul (R-Kentucky), agree with him on the issue.

"Well, I hate to say it, but Donald Trump has a bit of a point here," Paul said Wednesday night.

'Alter how we view ourselves as a nation'

The story was the same last month.

Almost immediately after Trump released his immigration plan, multiple Republican presidential candidates - many of whom are hoping to steal some of Trump's current supporters if he eventually flames out - came out in favor of ending birthright citizenship for children of immigrants living in the country illegally.

Louisiana Gov. Bobby Jindal and Wisconsin Gov. Scott Walker, both Republicans, said they were in favor of ending birthright citizenship. Sen. Lindsey Graham (R-South Carolina), no fan of Trump, in an interview on CNN decried "birth tourism" and said he would like to see the policy of birthright citizenship ended.

They join Paul, Republican New Jersey Gov. Chris Christie, and former Sen. Rick Santorum (R-Pennsylvania), who have all expressed varying degrees of support for changing the 14th Amendment in the past.

The renewed enthusiasm around the idea has the potential to put Republicans in a politically perilous position. It comes one presidential-election cycle after Republican presidential nominee Mitt Romney was walloped by 45 points among Latino voters against President Barack Obama in 2012.

Democrats and pro-immigration-reform activists have been quick to condemn the idea, claiming that changing the concept of birthright citizenship would alter the founding idea of the US as an immigrant-friendly country.

"It would be a constitutional change that would really alter how we view ourselves as a nation, and how we've thought about what it means to belong," Melissa Keaney, a staff attorney at the pro-reform National Immigration Law Center, told Business Insider last month.

"It's a radical idea that's seeming less radical because it's being talked about among" numerous Republican candidates, Keaney added.

"Deeply seeded, basically racist intentions"

Trump's support has brought renewed attention to the issue, but birthright citizenship has been debated by policymakers for a long time.

Though it has been accepted since the country's founding, birthright citizenship was clarified with the ratification of the 14th Amendment to the US Constitution in 1868. The amendment made it clear that slaves and their descendants were US citizens.

The debate has gained and lost momentum over the past several decades, but anti-illegal-immigration advocates have long maintained that the amendment has become outdated - and that it's now ripe for exploitation.

"When this thing was drafted, you'd be lucky to meet someone who was more than 30 miles away from where you were living," Stein, president of the Federation for American Immigration Reform, told Business Insider last month.

"Today's erroneous interpretation of the 14th Amendment is defeating the operation of US immigration controls. It is trumping the legislative intent of the statutes. It is rewarding illegal immigration and making the laws unenforceable," he added.

Immigrant advocates disagree. They point to coded terms like "anchor babies" and "birth tourism" by those who advocate changing the amendment as thinly veiled racist slights.

"It's pretty gross, and underlying are deeply seeded, basically racist intentions," Keaney told Business Insider.

Laura Epstein, a spokeswoman for the progressive group People for the American Way, added: "Clearly, their support for this indefensible policy shows that Republicans are more concerned with pandering to their anti-immigrant base than they are with producing real policy ideas to fix our broken immigration system."

Despite momentum on the right, it seems unlikely that the renewed vigor will produce serious results.

Legal experts contend that the US Supreme Court has left little ambiguity about the fact that individuals born in the United States are entitled to citizenship. Any effort to change that would likely have to include a constitutional amendment, which would be impossible to accomplish without an overwhelming bipartisan mandate. It requires a two-thirds "supermajority" in Congress, plus ratification from three-fourths of the states.

For his part, Trump said during the debate Wednesday that he has consulted with a "lot of great legal scholars" who tell him the law could be changed more unilaterally.

"But I believe that a reading of the 14th Amendment allows you to have an interpretation where this is not legal and where it can't be done. I've seen both sides, but some of the greatest scholars agree with me, without having to go through Congress," Trump said, declining to name any of the legal scholars.

As NPR has reported, the United States is one of the only countries that grants automatic citizenship based on if a person is born in the country. Most instead grant citizenship based on lineage, an idea that resonates strongly with conservative-leaning immigration activists in the US.

Immigration advocates also say that ending birthright citizenship would cause a host of problems. Keaney said that ending birthright citizenship would essentially render thousands of would-be citizens stateless, or at least leave them in an international legal limbo.

"What is your solution for dealing with this, for these individuals who would be American in every single way, knowing no other place other than the United States as home, speaking no language other than English?" Keaney said.

"Lowest form of political buffoonery"

Despite the fact that few political observers believe Trump will ultimately win the Republican nomination, he has had overwhelming success in bringing controversial immigration ideas and solutions to the center of the conversation in the Republican primary.

"Donald Trump has provided the opening opportunity to really start having a meaningful conversation that involves tough decisions," Stein said.

Earlier this summer, Trump was one of the first major candidates to speak out against "sanctuary cities," an umbrella term that refers to local governments that do not comply with US Immigration and Customs Enforcement orders to indefinitely detain suspected immigrants without probable cause.

But while the Republican push to defund sanctuary cities enjoys fairly broad support in the polls and is somewhat politically safe, support for amending the Constitution or ending birthright citizenship is more politically dubious.

The last major polls on the subject, taken in 2010, show that Americans were virtually split on whether to end birthright citizenship.

Democrats have already attempted to capitalize on Republican support for ending birthright citizenship.

"Criminalizing children - let alone citizen children born to immigrant parents - is the lowest form of political buffoonery … even for the GOP," Pablo Manriquez, director of Hispanic Media for the Democratic National Committee, told Business Insider.

And several Republican candidates who are considered serious contenders if they win their party's nomination have all hesitated to come out strongly against birthright citizenship.

Sen. Marco Rubio (R-Florida) said last month he would not support repealing the 14th Amendment. Former Florida Gov. Jeb Bush, a Republican, also dismissed the question, saying that there are "10 things I would change in the Constitution with a magic wand."

And in the debate Wednesday night, former Hewlett Packard CEO Carly Fiorina demurred when asked about the topic, saying it was unrealistic to expect to change a constitutional amendment.

"The truth is, you can't just wave your hands and say, 'The 14th Amendment is going to go away,'" she said. "It will take an extremely arduous vote in Congress, followed by two-thirds of the states, and if that doesn't work to amend the Constitution, then it is a long, arduous process in court."