The citizenship proposal would inevitably spark a long-shot legal battle over whether the president can alter the long-accepted understanding that the 14th Amendment grants citizenship to any child born on US soil, regardless of his parents' immigration status.
Trump noted a 1993 speech by Harry Reid on the Senate Floor a day after he stunned lawmakers by announcing he planned to sign an executive order to end birthright citizenship to non-residents. "That's what it costs ― billions". In the 1898 decision United States v. Wong Kim Arc, the High Court ruled that a Chinese-American man who was born in the U.S.to parents who were Chinese nationals was a United States citizen.
Trump doubled down on his commitment to upending the 14th Amendment to the riled-up crowd chanting, "USA!"
Hao Junbo, a Beijing-based lawyer experienced in cross-border litigation and USA law, said that even if Trump issued the executive order, it could be rejected for violating the United States constitution. "We will get rid of all of this".
Speaking to reporters before leaving the White House for a campaign rally in Florida, Trump compared his plan to act by executive order to President Barack Obama's much-maligned decision to use executive action to provide protections from prosecution and a path to work status for some people brought to the USA illegally as children.
"We're the only country in the world where a person comes in and has a baby, and the baby is essentially a citizen of the United States ... with all of those benefits", Trump told Axios.
Trump and many top aides have long seen the immigration issue as the most effective rallying cry for his base of supporters.
The Supreme Court has never ruled squarely about the clause's application to children of immigrants who are in the US illegally.
Napolitano said the 14th Amendment has been interpreted by courts to mean the same thing for 150 years.
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Since then, however, illegal immigrants or visitors on tourist visas have used the law to obtain citizenship for their children who are born on U.S. soil. However, White House lawyers expect to work with the Justice Department to develop a legal justification for the action.
Tyler Moran, the director of the Immigration Hub, which advises a wide range of progressive organisations on immigration policy, said that the moderates taking a more conservative tack on immigration were the outliers and that congressional and gubernatorial candidates nationwide were largely "rejecting Trump's strategy of lies and division". An end to the Constitution's guarantee of birthright citizenship.
Mr Trump said the soon-to-retire House of Representatives speaker should not be opining on "something he knows nothing about".
The Amendment reads "all persons born or naturalised in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside".
Trump repeated his claim that he can eliminate birthright citizenship via executive order later Wednesday, although he said his preference would be for Congress to pass legislation ending that constitutional right.
In the run-up to the November 6 congressional elections, Trump has seized on a caravan of migrants from Central America who are trekking through Mexico toward the United States, calling the migrants a threat.
He referenced court rulings later that "only children of legal residents are citizens" and that "Congress could clarify legislatively that the children of noncitizens are not subject to the jurisdiction of the United States, and thus not citizens under the 14th Amendment".
Most legal scholars say the jurisdiction language denies citizenship only to those who are not bound by US law, such as the children of foreign diplomats.
"I'd rather do it through Congress because that's permanent, but we can certainly do it through - I really (believe) we can do it through executive order", he added, noting he had discussed the issue with legal scholars.