WASHINGTON (AP) — President Barack Obama argued Friday for keeping a key provision of federal voting rights law in place, saying it will become harder but not impossible to help people who believe their rights at the polls have been violated if the Supreme Court decides to strike down that part of the law.

The court has scheduled oral arguments for Wednesday on a challenge from Shelby County, Ala., near Birmingham, to a section of the Voting Rights Act. The provision requires all or parts of 16 states with a history of racial discrimination, mostly in the South, to get approval from the Justice Department or federal court in Washington before making any changes in the way they hold elections, such as moving a polling place.