SELMA, Ala. (AP) — Black leaders commemorating a famous civil rights march on Sunday said efforts to diminish the impact of African-Americans' votes haven't stopped in the years since the 1965 Voting Rights Act added millions to Southern voter rolls.

Hundreds gathered Sunday morning for a brunch with Vice President Joe Biden, and thousands were expected Sunday afternoon to march across the Edmund Pettus Bridge in Selma's annual Bridge Crossing Jubilee. The event commemorates the "Bloody Sunday" beating of voting rights marchers by state troopers as they began a march to Montgomery in March 1965. The 50-mile march prompted Congress to pass the Voting Rights Act that struck down impediments to voting by African-Americans and ended all-white rule in the South.

Biden said nothing shaped his consciousness more than watching TV footage of the beatings. "We saw in stark relief the rank hatred, discrimination and violence that still existed in large parts of the nation," he said.

Biden said marchers "broke the back of the forces of evil," but challenges to voting rights continue today with restrictions on early voting and voter registration drives and enactment of voter ID laws where no voter fraud has been shown.

Jesse Jackson said Sunday's event had a sense of urgency because the U.S. Supreme Court heard a request Wednesday by a mostly white Alabama county to strike down a key portion of the Voting Rights Act.

"We've had the right to vote 48 years, but they've never stopping trying to diminish the impact of the votes," Jackson said.

Referring to the Voting Rights act, the Rev. Al Sharpton said: "We are not here for a commemoration. We are here for a continuation."

The Supreme Court is weighing Shelby County's challenge to a portion of the law that requires states with a history of racial discrimination, mostly in the Deep South, to get approval from the Justice Department before implementing any changes in election laws. That includes everything from new voting districts to voter ID laws.

"At least when you went to the Justice Department, you felt you had one more chance of getting justice when you weren't getting it at home," Alabama Senate Democratic leader Vivian Davis Figures of Mobile said.

Attorneys for Shelby County argued that the pre-clearance requirement is outdated in a state where one-fourth of the Legislature is black. But Jackson predicted the South will return to gerrymandering and more at-large elections if the Supreme Court voids part of the law.

One of the NAACP attorneys who argued the case, Debo Adegbile, said when Congress renewed the Voting Rights Act in 2006, it understood that the act makes sure minority inclusion is considered up front.

"It reminds us to think consciously about how we can include all our citizens in democracy. That is as important today as it was in 1965," he said.

Adegbile said the continued need for the law was shown in 2011 when undercover recordings from a bribery investigation at the Alabama Legislature included one white legislator referring to blacks as "aborigines" and other white legislators laughing.

"This was 2011. This was not 1965," he said.