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Darron Cummings, Associated Press
Sen. Richard Lugar meets with voters outside of a polling location Tuesday, May 8, 2012, in Greenwood, Ind. Lugar is being challenged by two-term state Treasurer Richard Mourdock.

It's official: Sen. Richard Lugar, R-Ind., lost Tuesday's Republican primary in Indiana.

"Lugar — the longest-serving senator in Indiana history — will lose his Republican Senate primary on Tuesday to state Treasurer Richard Mourdock, CBS News projected Tuesday evening.

Meanwhile, Sen. Orrin Hatch — like Lugar, Hatch is running for a seventh term — is doing all he can to ensure he doesn't suffer a similar fate in Utah's primary on June 26. Indeed, the Lugar loss inevitably brings Hatch into a discussion about the political survival of tenured senators, given that Lugar and Hatch both joined the U.S. Senate on Jan. 3, 1977, and have even publicly squabbled with each other over which one of the two is higher in terms of Senate seniority among Republicans.

In August, the Deseret News examined the re-election prospects of Lugar and Hatch. Lugar's political director said at the time, "We're way out in front of where this is going to go."

As recently as a month ago, popular opinion held that Lugar would find a way to prevail over Mourdock. Bloomberg Politics, for example, opined on April 17 that "It would be unusual if either (Lugar or Hatch) lost."

Hatch's opponent in the June primary is Dan Liljenquist. Two weeks ago, Politico's Charlie Mahtesian wrote, "While Hatch is the solid favorite to win the June 26 primary, when the broader Republican electorate will be more favorably inclined toward him than the small base of convention attendees, hes not home free."