WASHINGTON — President Barack Obama says all Americans owe a debt to the sharecroppers and maids and ordinary Americans who were brave enough to try time and again to register to vote in the face of violence and oppression. He says without them, the Voting Rights Act wouldn’t have been signed into law 50 years ago Thursday.

At a White House event marking the anniversary, Obama said those rights are being whittled away today by voter ID laws and other attempts to discourage voting. He called on Congress to update the law in response to court decisions.

But Obama says attacks on their voting rights aren’t the main reason Americans don’t vote — many just don’t bother.

He declared Sept. 22 National Voter Registration Day and urged everyone to get registered.