President Trump is joined by Homeland Security Secretary John Kelly during a visit to the Department of Homeland Security on Jan. 25. (Chip Somodevilla/Getty Images)

A prominent advocate of ending U.S. birthright citizenship is in line to join the Trump administration in an immigration-related position at the Department of Homeland Security, according to two former U.S. officials informed of transition changes by department personnel.

Jon D. Feere has been a legal policy analyst for the Center for Immigration Studies, a conservative group that calls for added immigration restrictions.

Reached Tuesday by a Washington Post reporter, Feere said, “I’m in between jobs. That’s all I can say right now. I can’t confirm anything” about accounts circulating among some current and former DHS officials that he would join the department in an immigration enforcement post.

Feere, 37, testified before the House Judiciary subcommittee on immigration in 2015 and has written several opinion pieces, including an August 2015 article in TheHill.com, proposing alternatives to a constitutional amendment by which Congress could enact a law or President Trump could issue an executive order denying citizenship, U.S. passports or Social Security numbers to American-born children of people in the country illegally.

Feere in 2010 estimated those births at between 300,000 and 400,000 a year, according to information on the CIS website. Other estimates put the figure lower. About 275,000 babies were born to unauthorized-immigrant parents in 2014, according to Pew Research Center estimates based on government data.

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“President Obama has demonstrated that unilateral action by the executive branch is a legitimate means of changing the nation’s immigration policy,” Feere wrote in his 2015 article. “Though his actions have been controversial, executive actions that direct agencies how to approach birthright citizenship are arguably more justifiable.”

Feere added, “Whether Trump worked with Congress to draft legislation or simply directed agencies to apply the Citizenship Clause more narrowly, the issue would likely end up at the Supreme Court.”

Feere’s name surfaced as GOP congressional judiciary committee staffers were said by former officials to be in the running for other homeland security positions. Those under consideration reportedly include Tracy L. Short, a House panel counsel who formerly served as deputy chief counsel with U.S. Immigration and Customs Enforcement’s Atlanta office, and Gene P. Hamilton, a Senate panel counsel for Sen. Jeff Sessions (R-Ala.), Trump’s pick for attorney general.

Spokeswomen for Sessions and the House committee did not return requests for comment Wednesday, and Short and Hamilton did not respond to email messages seeking comment.

The administration’s potential staffing moves come under a spotlight as Trump began signing executive orders Wednesday on immigration matters including enabling construction of his proposed wall on the U.S.-Mexico border.

Sessions has been an advocate of a tougher crackdown on immigration, although it remained unclear what steps Trump may undertake regarding the Obama administration’s Deferred Action for Childhood Arrivals program, known as DACA. The 2012 initiative has given temporary protection from deportation to hundreds of thousands of people who arrived in the United States as children. Trump vowed during the campaign to reverse it.

Denying citizenship to U.S. born children of illegal immigrants would open a new battleground.

“If there is a policy tug of war between the [Trump chief strategist Stephen K.] Bannon faction and the [chief of staff Reince] Priebus faction . . . assuming those things even exist, there’s still lots of hawkish people likely to be appointed in the various agencies,” said Mark Krikorian, CIS executive director. Krikorian declined to comment about Feere.

“Personnel is policy, and the people getting the important policy positions in places like ICE and Customs and Border Protection are likely to be pretty strong pro-enforcement people, as opposed to Bush administration leftovers,” Krikorian said.

Feere and other critics of birthright citizenship have argued government action is needed because of the numbers of such children, and what they say is a rise of “birth tourism” and a phenomenon of “chain migration” in which U.S. citizens can sponsor immediate family members to come into the country.

When Congress considered legislation in 1995 to end automatic citizenship for children born to people who entered the U.S. illegally, opponents said it would contradict U.S. constitutional history and tradition and said the 14th Amendment established a “bright-line” principle that being born on American soil makes one a U.S. citizen.

The amendment was passed in response to the 1856 Dred Scott decision by the U.S. Supreme Court that found that no person of African descent could ever become a citizen, and was upheld in 1898 by the court in a challenge to the Chinese Exclusion Act, which prohibited anyone of Chinese ancestry from remaining in the country.

Defending the principle in an NPR interview in 2010, former assistant attorney general and acting solicitor general Walter Dellinger traced it to America’s racial history and immigrant identity.

“We believe in a clean slate principle” and that “whatever questions there are about the legitimacy of parents or grandparents, in our country, you get a clean slate,” Dellinger said. “Every new child who is born here is simply and indisputably an American. And that is part of our almost unique national identity.”