Members of the media set up equipment Tuesday in front of the Lincoln Memorial in Washington, for the 50th anniversary of the March On Washington celebrations that will be held today.

WASHINGTON — President Barack Obama won't need to mention race — a subject he doesn't talk a lot about in public — when he stands at the Lincoln Memorial on the anniversary of the March on Washington.

His presence at the commemorative ceremony today will embody the fulfilled dreams of the hundreds of thousands who rallied there 50 years ago for racial equality — and will personify the continued struggle for that elusive goal.

When he became president, Obama blasted through a heavy barrier that many before him had only pushed against. But his presidency has been marred by racist backlash and his administration has found itself refighting battles already thought won, such as ensuring equal access to the polls.

Obama is expected to speak just after an organized ringing of bells by churches and others at 3 p.m., the time when the Rev. Martin Luther King Jr. delivered his spellbinding “I Have a Dream” speech.

Obama will be joined by former Presidents Jimmy Carter and Bill Clinton at the memorial's steps. Other luminaries include Lynda Bird Johnson Robb, daughter of President Lyndon Johnson, who signed the 1964 Civil Rights Act and the 1965 Voting Rights Act.

Former President George W. Bush — still recuperating from a heart procedure this month — will not attend the celebration.

A march, led by a replica of a transit bus that civil rights leader Rosa Parks rode when she refused to give up her seat to a white man in 1955, and an interfaith service also were planned for Wednesday morning. A march held Saturday drew tens of thousands to the Lincoln Memorial.