WASHINGTON -- Oprah Winfrey, Jamie Foxx and Forest Whitaker are among the celebrities joining three presidents this week to mark the 50th anniversary of the March on Washington.

Soledad O'Brien and Hill Harper will host the "Let Freedom Ring" commemoration of Martin Luther King Jr.'s "I Have a Dream speech on Wednesday. President Barack Obama and former presidents Bill Clinton and Jimmy Carter are also joining the tribute at the Lincoln Memorial.

Georgia Rep. John Lewis, who spoke at the 1963 March on Washington, will speak at this year's march, along with Winfrey, Foxx and Whitaker.

Winfrey and Whitaker are starring in "Lee Daniels' The Butler," a movie about a man who served for seven presidents as a White House butler.

Musicians including LeAnn Rimes and BeBe Winans are scheduled to perform.

Also on HuffPost:

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  • March On Washington 50th Anniversary

    Crowds gathered at the Lincoln Memorial for the 50th anniversary of the March on Washington on August 24, 2013 (Ryan J. Reilly / The Huffington Post).

  • Nancy Pelosi, Martin Luther King III, Andrea King, Al Sharpton, John Lewis

    The Rev. Al Sharpton, center, arm-in-arm with Congressman John Lewis, lines up with Martin Luther King, III, third from right, and his wife Arndrea King, and Speaker of the House Nancy Pelosi, second from left, prepare for the start of the march towards the Martin Luther King Jr. Memorial after the rally at the Lincoln Memorial, commemorating the 50th anniversary of the 1963 March on Washington Saturday, Aug. 24, 2013. (AP Photo/Jose Luis Magana)

  • March On Washington 50th Anniversary

    (Ryan J. Reilly/The Huffington Post).

  • Ben Jealous

    Ben Jealous, the president of the NAACP, speaks at the Lincoln Memorial during the 50th Anniversary of the March on Washington (Ryan J. Reilly / The Huffington Post).

  • Trayvon Martin's Family

    The family of Trayvon Martin marched at the front of the line alongside Rep. Nancy Pelosi (D-Calif.), Rep. John Lewis (D-Ga.), Rev. Al Sharpton and Martin Luther King III (Ryan J. Reilly / The Huffington Post).

  • John Lewis

    Rep. John Lewis, D-Ga., speaks during the 50th anniversary commemoration of the 1963 March on Washington at the Lincoln Memorial, Saturday, Aug. 24, 2013, in Washington. Tens of thousands of people marched to the Martin Luther King Jr. Memorial and down the National Mall on Saturday, to commemorate King's famous ""I Have a Dream" speech, delivered Aug. 28, 1963, during the March on Washington, and pledging that his dream includes equality for gays, Latinos, the poor and the disabled. (AP Photo/Carolyn Kaster)

  • March On Washington 50th Anniversary

    Crowds gathered around the reflecting pool by the Lincoln Memorial during the 50th anniversary of the March on Washington (Ryan J. Reilly / The Huffington Post).

  • Attorney General Eric Holder

    Attorney General Eric Holder speaks at the 50th Anniversary of the March on Washington (Ryan J. Reilly / The Huffington Post).

  • March On Washington 50th Anniversary

    (Ryan J. Reilly/The Huffington Post).

  • Sabrina Fulton, Jahvaris Fulton, Al Sharpton, Tracy Martin

    Sabrina Fulton, mother of slain teenager Trayvon Martin, speaks at the podium in front of the Lincoln Memorial in Washington Saturday, Aug. 24, 2013, with Rev. Al Sharpton, left, Tracy Martin, father of Trayvon Martin, second from right, and Jahvaris Fulton, brother of Trayvon Martin, right, during the 50th anniversary commemoration of the of the Aug. 28, 1963, March on Washington. (AP Photo/Carolyn Kaster)

  • March On Washington 50th Anniversary

    Volunteers lined up at the front of the march before it began (Ryan J. Reilly/The Huffington Post).

  • Rep. John Conyers, Attorney General Eric Holder

    Rep. John Conyers (D-Mich.) poses with Attorney General Eric Holder (Ryan J. Reilly/The Huffington Post).

  • March on Washington 50th Anniversary

    A sign marked where Martin Luther King III, Rep. John Lewis (D-Ga.) and Rev. Al Sharpton stood at the start of the march (Ryan J. Reilly/The Huffington Post).

  • March On Washington 50th Anniversary

    Marchers made their way around the Tidal Basin. The Jefferson Memorial can be seen in the background (Ryan J. Reilly / The Huffington Post).

  • Crowds rally at the Lincoln Memorial in Washington to commemorate the 50th anniversary of the 1963 March on Washington Saturday, Aug. 24, 2013. Fifty years ago, on the actual anniversary, April 28, 1963, Dr. Martin Luther King Jr. deliver his "I Have a Dream" speech during the March on Washington. (AP Photo/Jose Luis Magana)

  • March On Washington 50th Anniversary

    Young marchers with a local NAACP chapter (Ryan J. Reilly / The Huffington Post).

  • March On Washington 50th Anniversary

    A large crowd marched along Independence Ave. (Ryan J. Reilly/The Huffington Post).

  • March On Washington 50th Anniversary

    The parents of Trayvon Martin and Rep. Steny Hoyer (D-Md.) at the front of the March (Ryan J. Reilly/The Huffington Post).

  • March On Washington 50th Anniversary

    The front of the march heads over Kutz Bridge by the Jefferson Memorial (Ryan J. Reilly/The Huffington Post).

  • Rev. Al Sharpton And Martin Luther King III

    Rev. Al Sharpton and Martin Luther King III marching (Ryan J. Reilly/The Huffington Post).

  • Rep. John Lewis And Al Sharpton

    Rep. John Lewis (D-Ga.) and Rev. Al Sharpton at the front of the march (Ryan J. Reilly/The Huffington Post).

  • Civil Right Leader Joseph Lowery

    Civil rights leader Joseph Lowery (Ryan J. Reilly/The Huffington Post).

  • In this combination of Associated Press file photos, at top, a crowd gathers in front of the Lincoln Memorial during the March on Washington for civil rights, on Aug. 28, 1963; and at bottom, people attend a rally to commemorate the 50th anniversary of the 1963 March on Washington at the Lincoln Memorial in Washington, Saturday, Aug. 24, 2013. Organizers were planning for nearly 100,000 to attend Saturday. Minutes before key speeches began, buses were backed up still trying to the reach the site. (AP Photo/File)

  • In this combination of Associated Press file photos, at top, a large crowd marches for civil rights in Washington on Aug. 28, 1963; and at bottom, demonstrators march towards the Martin Luther King Junior Memorial during a rally to commemorate the 50th anniversary of the 1963 march on Saturday, Aug. 24, 2013. Aging veterans of the original March on Washington gathered with younger generations Saturday amassing a crowd that in contrast was more female, more Hispanic, and more diverse by sexual orientation than in 1963. (AP Photo/File)

  • In this combination of Associated Press file photos, at left, a mass of demonstrators leaves the Washington Monument for the March on Washington on Aug. 28, 1963; and at right, people line the Reflecting Pool as they attend a rally to commemorate the 50th anniversary of the 1963 march on Saturday, Aug. 24, 2013, in Washington. Fifty years after the Rev. Martin Luther King Jr. offered a transcendent vision of racial harmony for America's future with his "I Have a Dream" speech, tens of thousands gathered where he spoke Saturday to hear leaders tell them that while much has been attained, much remains unfinished. (AP Photo/File)

  • In this combination of Associated Press file photo, at top, large crowds gather at the Lincoln Memorial to demonstrate for civil rights in Washington, on Aug. 28, 1963; and at bottom, participants gather on the same steps to commemorate the 50th anniversary of the 1963 march, Saturday, Aug. 24, 2013, in Washington. The 2013 event was an homage to a generation of activists that endured fire hoses, police abuse and indignities to demand equality for African Americans. (AP Photo/File)

  • In this combination of Associated Press file photos, at top, civil rights protestors march down Constitution Avenue carrying placards during the March on Washington on Aug. 28, 1963; and at bottom, people rally at the Lincoln Memorial in Washington to commemorate the 50th anniversary of the 1963 march Saturday, Aug. 24, 2013. Dr. Martin Luther King Jr. delivered his "I Have a Dream" speech during the March on Washington on Aug. 28, 1963. (AP Photo/File)