President Donald Trump plans to abolish the right to citizenship for anyone born in the United States - guaranteed by the 14th Amendment to the US Constitution - with an executive order, he said in an interview excerpt released Tuesday.
"You can not end birthright citizenship with an executive order", Mr Ryan told Kentucky-based radio station WVLK. "So-called Birthright Citizenship, which costs our Country billions of dollars and is very unfair to our citizens, will be ended one way or the other", he wrote on Wednesday.
Schuck, of Yale, and colleague Rogers Smith of the University of Pennsylvania have argued since the mid-1980s that Congress can set the rules for providing citizenship to US -born children of parents who came illegally. And most legal scholars say it would take a new constitutional amendment to alter the current one granting citizenship to anyone born in America.
"I think the President's argument is actually pretty strong" says Smith. "We will get rid of all of this". If the President tries to enact gun control legislation like Barack Obama tried to do through executive order that's not really going to fly.
Under the Constitution's 14th Amendment, enacted in the wake of the Civil War to ensure that black Americans previously subject to slavery had full citizenship rights, citizenship is granted to "all persons born or naturalized in the United States".
Top Democrat Nancy Pelosi called Mr Trump's claim an example of "Republican's spiralling desperation to distract from their assault" on healthcare.
The 14th Amendment was a response to the Supreme Court's 1857 decision in Dred Scott v. Sandford, which said that slaves and their children were not US citizens and therefore, could not sue in federal courts.
An executive order would spark an uphill legal battle for Trump about whether the president has the unilateral ability to declare that children born in the United States to those living here illegally aren't citizens.
Napolitano said the 14th Amendment has been interpreted by courts to mean the same thing for 150 years. Former White House official Michael Anton argued in The Washington Post last July that the amendment is being misread.
During the Axios interview, Trump complained, "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 has railed against illegal immigration, including several caravans of migrants from Central America slowly moving toward the US border. Birthright citizenship, Mr Gude told The National "is in both the Constitution and statute".
Saikrishna Prakash, a conservative legal scholar at the University of Virginia, said Trump faces long legal odds to ending citizenship as a birthright. Six of the Justices ruled that the phrase "and subject to the jurisdiction thereof" applied to any person required to obey U.S. laws, meaning even children of foreigners residing in the country permanently or temporarily.
Trump denied when asked by a reporter if he is merely stoking fears about undocumented migrants before a crucial election.
Most legal scholars say the jurisdiction language denies citizenship only to those who are not bound by USA law, such as the children of foreign diplomats.
The country is facing a massive backlog of immigration cases - some 700,000 - and there are more and more families coming across the border from Central America - groups who can not be simply returned over the border.