WASHINGTON (AP) -- Vying for the support of a key Democratic constituency, presidential hopefuls Hillary Rodham Clinton and Barack Obama have signed on to speak at an annual civil rights commemoration in Selma, Ala., on Sunday at the same time and just a few doors down from each other.

State Democratic leaders and event organizers said they couldn't remember a time when two leading presidential candidates spoke at the Bridge Crossing Jubilee, held annually in honor of the 1965 Selma-to-Montgomery voting rights march.

"It's a first," said Tarana Burke, a spokeswoman for Selma's National Voting Rights Museum and Institute, which sponsors the event. "Both of them are directly affected by the voting rights movement, and we're glad they appreciate that enough to come and help us commemorate."

Clinton, a Democratic senator from New York, is scheduled to headline the 10 a.m. service at First Baptist Church and to represent her husband, former President Bill Clinton, at his induction into the museum's hall of fame, Burke said.

Obama, a Democratic senator from Illinois who is black, is slated to speak at a "Unity Breakfast" and deliver the event's keynote address at the 10 a.m. service at Brown Chapel A.M.E. Church.

Both churches were sites where organizers and marchers met in the historic protests that helped lead to greater ballot access across the South for blacks.

State Democratic leaders estimated 40 to 50 percent of Democratic primary voters in Alabama are black. Organizers say several dozen members of Congress also plan to attend, along with former presidential candidates Jesse Jackson and Al Sharpton. A spokesman for Clinton said the senator is still finalizing details of her visit.