U.S. President Donald Trump said he plans to sign an executive order ending birthright citizenship for babies of non-citizens and unauthorized immigrants born on U.S. soil, a proposal one legal expert called "absurd."

“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,” Trump told “Axios on HBO” in an interview, excerpts of which were released Tuesday. “It’s ridiculous. And it has to end.”

Trump’s claim that the U.S. is the only country that extends birthright citizenship is false. While the president is correct that European countries all require a period of residency before bestowing citizenship on those born to foreign parents, many countries in the Americas such as Canada, Mexico, Brazil and Argentina have U.S.-style birthright citizenship.

Trump asserted that it would not take a constitutional amendment to rescind birthright citizenship from some people born in the U.S., a stance that would undoubtedly draw a legal challenge should he proceed.

"It was always told to me that you needed a constitutional amendment. Guess what? You don’t," he said.

The 14th Amendment to the U.S. Constitution spells out birthplace as an arbiter of citizenship, stating that, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States."

Sarah Turberville, a constitutional expert at the Project on Government Oversight, an independent nonprofit, said Trump’s proposal would be ripe for a court challenge from those stripped of citizenship. It would also likely prompt bipartisan congressional charges of executive overreach, Turberville said.

“It’s a pretty absurd notion frankly that the president believes he would be able to amend the Constitution and 150-plus years of interpreting the 14th Amendment through an executive order,” Turberville said in an interview Tuesday.

Trump’s proposal comes a exactly a week before lawmakers midterm elections, in which Trump’s Republican Party is bracing for heavy losses and a potential Democratic takeover of the U.S. House.

The move could give a boost to Trump’s fellow immigration hard-liners. Maine Senate candidate Eric Brakey, a Republican who is challenging incumbent Angus King, endorsed Trump’s plan in a statement, saying the president “needs fresh support in Congress to follow through.”

But moderate Republican Representative Carlos Curbelo, who is in a competitive race to keep his South Florida seat, distanced himself from Trump, tweeting that birthright citizenship "is protected by the Constitution."

"What we really need is broad immigration reform that makes our country more secure and reaffirms our wonderful tradition as a nation of immigrants," Curbelo said.

“The president cannot erase the Constitution with an executive order, and the 14th Amendment’s citizenship guarantee is clear," Omar Jadwat, director of the ACLU’s Immigrants’ Rights Project, said in a statement. “This is a transparent and blatantly unconstitutional attempt to sow division and fan the flames of anti-immigrant hatred in the days ahead of the midterms.”

Asked about timing or legal justification for the executive order, White House Press Secretary Sarah Sanders said only that the full interview with the president would air Sunday.

Trump has been trying to restore the public focus on immigration after the events of the past week, which included the arrest of a Trump supporter in connection with mailing at least 13 suspected explosive devices to targets of the president’s ire, including Democratic politicians and the cable network CNN. In another incident, a gunman on Saturday shot and killed 11 people in a Pittsburgh synagogue in what authorities have said was a hate crime.

After an initial call for unity, Trump has increased his rhetoric against the media and undocumented immigrants, including a group of Central American migrants that is heading toward the U.S. through Mexico. The Trump administration announced Monday that it would send about 5,200 troops to the southern border with Mexico by the end of the week to head off the migrants.

Secretary of State Mike Pompeo in September said the U.S. planned to lower the cap on refugee admissions by a third to a record low 30,000 people for the coming fiscal year. Immediately after taking office in January 2017, Trump attempted to ban entrants from several Muslim nations, an effort that was turned down by the courts and forced his administration to rewrite the policy before the U.S. Supreme Court in June upheld the latest iteration.

Axios said its full interview with Trump would air Sunday.