President Obama participates in an interview with Robin Roberts of ABC's Good Morning America in the White House on May 9. During the interview, Obama expressed his support for gay marriage, a first for a U.S. president. The White House/Getty Images hide caption

itoggle caption The White House/Getty Images

Lugar, in the Senate 34 years, faces a strong Tea Party challenge in next year's GOP primary. Alex Brandon/AP hide caption

itoggle caption Alex Brandon/AP