Donald Trump is back at the White House as the 47th president of the United States. On his first day, Trump signed executive orders that will make it harder for refugees to stay in the country. He also vowed to try to end birthright citizenship in the country.

Donald Trump is trying to redefine who is allowed to be a U.S. citizen. On the first day of his presidency, Trump signed an order challenging a long-standing constitutional right that people born inside the U.

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.