Centrist Sen. Richard Lugar (R) of Indiana has been in office since 1977. Tea party-challenger Richard Mourdock has attacked him from the right and looks set to win Tuesday's GOP primary.
Indiana voters appear close to dealing long-time Sen. Richard Lugar (R) a major setback in Tuesday's Republican primary. His tea party-backed challenger, who says Senator Lugar isn't conservative enough and is out of touch with his home state, holds a sizeable lead, according to polls.
If dealt a primary loss, could Lugar mount a viable third-party run as an independent?
Sen. Joe Lieberman (I) of Connecticut, ejected in the 2006 Democratic primary, retained his seat by running under a new party flag, "Connecticut for Lieberman." Sen. Lisa Murkowski (R) of Alaska, after losing a primary in 2010, held her seat by winning as a write-in candidate.
Like them, Lugar has plenty of name recognition and a reserve of goodwill among voters in his home state. But several political analysts say they expect the Republican primary to determine the fate of Lugar's six-term Senate career, suggesting he's unlikely to run as a third-party candidate.