President Barack Obama didn’t wait for Congress to rewrite the nation’s immigration laws to help millions who are in the United States illegally stay in the country.

He halted deportations of those who came to the United States when they were young, those who care for children and those who haven’t committed crimes. And he’s started allowing some relatives of U.S. service members living in the country illegally to stay as a way to alleviate additional stress on the military and reward veterans.

With a proposed immigration overhaul stalled in Congress, Obama is changing the policy step by step on his own. He’s using executive actions to affect millions of people, part of a pattern he’s embraced on a variety of topics in recent years to bypass Capitol Hill.

“What this administration has undertaken has never happened to this degree,” said Mark Krikorian, the executive director of the Center for Immigration Studies, a research center.

Obama’s actions spark anger on both sides of the issue. Supporters of an immigration overhaul complain that he hasn’t gone far enough. Opponents of an immigration overhaul say he goes too far.