The president is now musing about trying to revoke Rosie O'Donnell’s birthright citizenship because he doesn’t like her

President Donald Trump says he is considering “taking away” the U.S. citizenship of a longtime rival, actress and comedian Rosie O’Donnell, despite a decades-old Supreme Court ruling that expressly prohibits such an action by the government.

Amid the uncertainty and potential changes in the naturalization process to be a U.S. citizen, here are five things to know.