Indiana's attorney general has issued a statement confirming a decades-old advisory that Sen. Richard Lugar (R-Ind.) has remained an Indiana resident even though he doesn't have a home in the state. 

It was a Pyrrhic victory for the six-term senator, because his residency is much more of a political than legal problem.

Lugar has lived primarily in the suburbs of Washington, not in Indiana, for 30 years, and his voting address in the Hoosier State is from a home he sold decades ago.  

Lugar's primary opponent, state Treasurer Richard Mourdock (R) has seized on the issue, as have Mourdock's Tea Party allies and Democrats hoping Lugar will lose the primary so they could have a better shot at the seat.

"The analysis and conclusions in the 1982 advisory letter remain valid," Matthew Light, chief counsel to Indiana Attorney General Greg Zoeller, said in the letter. "Members of Congress do not lose their residency for voting purposes when they leave the state so that they may fulfill their duties ... You have served continuously in the U.S. Senate as an Indiana Senator since 1977. To the extent you have been absent from the state since that time, the absence has been directly related to the business of the state of Indiana and the United States. Therefore the residence you established in Indiana is not lost by reason of that absence."

While Lugar is likely on safe ground legally, the question will come up again Friday when Indiana's election commission will review whether he can continue to vote from his old address.

Lugar is facing a tough challenge from Mourdock, who has the support of numerous conservative D.C.-based groups including the deep-pocketed Club for Growth.