Mr. Trump is planning to attempt to deny birthright citizenship to the children of immigrants who are in the U.S. illegally, according to the incoming officials. The U.S. government has long interpreted the U.S. Constitution to mean that those born on American soil are citizens at birth, regardless of their parents' immigration status.

Attorneys general in 18 states sued Tuesday to block the order, saying birthright citizenship cannot be undone with the stroke of the president’s pen.

Immigration rights groups, including the American Civil Liberties Union, sued the Trump administration soon after the president signed an executive order on immigration that would end birthright citizenship for children born in the U.