Ken Cuccinelli, the acting director of U.S. Citizenship and Immigration Services, speaks during an Aug. 12 briefing at the White House. (Evan Vucci/AP)

The Trump administration scrambled Thursday to contain a political firestorm that erupted over a highly technical policy that officials say will affect the citizenship applications of “a very small” number of children born abroad to U.S. servicemembers and federal employees.

Some initial news reports said the administration’s new policy would broadly bar such children from automatic U.S. citizenship, but federal officials said it would affect only children whose families fall into atypical categories: children adopted overseas by government workers or military members, children whose parents weren’t citizens when they were born, and children of Americans who didn’t meet the residency requirements needed to automatically transmit citizenship at birth.

Officials for U.S. Citizenship and Immigration Services estimated that the policy, which goes into effect Oct. 29, would affect 20 to 25 people a year, while the Pentagon said it may affect fewer than 100 a year.

Most American citizens can easily transmit citizenship to their children born abroad under federal law, and federal immigration and State Department officials emphasized that the policy would not change that. Instead, they said, the policy update resolves a long-standing bureaucratic dispute between the citizenship agency and the State Department.

USCIS said it updated its policy manual to eliminate conflicting rules between the Homeland Security and State departments that were making it difficult for some of these children to obtain passports from consular offices abroad.

Officials say the shift is mainly about paperwork: Parents who could not easily transmit citizenship to their child can still apply to naturalize them, though they have to file different forms.

USCIS officials, speaking on the condition of anonymity to explain the issue Thursday, said they reluctantly updated the policy because the State Department requested it.

“As a former Marine myself, I know the sacrifices our military families endure without complaint in service to their country, and the idea that this policy negatively impacts or takes anything away from them is absolutely incorrect,” one USCIS official said. “It bears repeating that this affects a very small population of individuals and they have another means of obtaining citizenship for their children.”

Widespread confusion over the policy update spread quickly Wednesday night amid conflicting media reports and fears that the Trump administration, which has curbed some protections for immigrants in the military, would make it difficult for children of American citizens overseas to obtain citizenship.

House Speaker Nancy Pelosi (D-Calif.) called the policy “shameful” and said it should be reversed. U.S. Rep. Joe Kennedy (D-Mass.) tweeted: “Not even those willing to die for this nation are spared his hate.”

USCIS acting director Ken Cuccinelli told Fox News late Wednesday that children would not be denied citizenship because of this new policy.

The issue stemmed from a conflict between two federal agencies that have jurisdiction over U.S. citizenship: USCIS, the Homeland Security agency that issues citizenship certificates; and the State Department, which issues passports and has a more powerful impact on the ability of families to obtain identification and freely travel.

USCIS had been issuing citizenship certificates to children of government employees and the military living abroad under section 320 of the Immigration and Nationality Act, which is only supposed to grant automatic citizenship to children born abroad and residing in the United States.

Officials said embassies and consular offices abroad wouldn’t issue passports to such children because they weren’t in the United States — they were overseas.

As a result, USCIS officially changed its written policy so that parents of children born abroad and still living there would have to apply for them to naturalize under section 322 of the act, a process that some immigration lawyers said could be more costly and cumbersome for families abroad.

The State Department said in a statement Thursday that it had been working with USCIS “for some time to align” the policies, which also line up with the Immigration and Nationality Act.

“This guidance is in line with existing, long-standing State Department policy on the interpretation of these terms,” the agency said in a statement.

Officials said USCIS had previously treated U.S. citizens living and working abroad in government service to be “residing in the United States,” leading to confusion.

Both groups can obtain citizenship, under separate sections of the immigration act and by filing different forms.

The policy is so bureaucratic — and affects so few people — that immigration lawyers and federal officials struggled at first to explain it.

“It’s extremely difficult to explain all the technical details,” said another federal official, who spoke on the condition of anonymity to explain the nuances of the policy. “And it’s easy to distort what’s actually happening here, which I think has happened in the last day or so.”

David Kubat, immigration lawyer in St. Paul, said that the policy adjustment is “definitely one of those things that are so complex that it is hard to describe,” and that anyone who is worried should talk to a lawyer.

But, he added, “Generally speaking, the vast majority of people are going to automatically derive citizenship at birth.”

Children born abroad to an American parent automatically become citizens at birth if they meet the requirements in sections 301 and 309 of the immigration act. Most easily obtain passports or more commonly, consular birth reports, from consulates and embassies overseas.

Last fiscal year, the State Department issued more than 64,500 birth reports to U.S. citizens abroad.

Missy Ryan contributed to this report.