Lynda Bird Johnson Robb (L), daughter of former U.S. President Lyndon Baines Johnson, former Senator Chuck Robb and journalist Maria Shriver clasp hands and sing "We Shall Overcome" before U.S. President Barack Obama arrives to speak at a Civil Rights Summit to commemorate the 50th anniversary of the signing of the Civil Rights Act in Austin, Texas April 10, 2014. REUTERS/Kevin Lamarque (UNITED STATES - Tags: POLITICS)