(CNN) - Sen. Dick Lugar, the third most senior member of the Senate, triumphed Friday over challenges to his eligibility to pursue re-election as a candidate from Indiana because he no longer has a home there.
Lugar, who has lived in McLean, Virginia, since the sale of his Indianapolis home in 1977, had insisted that residency was not an issue for him since the Indiana state constitution stipulates he only had to be a resident to run for Senate during his first campaign.
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Lugar's primary opponent, tea-party-backed state Treasurer Richard Mourdock, has made a campaign issue out of Lugar's lack of a physical residence in the Hoosier state.
But in a 4-0 decision Friday, the Indiana Election Commission agreed with Lugar and denied three voter challenges to his placement on the May 8 primary ballot.
"I don't think there's enough here to disqualify Sen. Lugar," said Anthony Long, vice-chair of the commission.
A day earlier, Lugar's position was also backed by Indiana Attorney General Greg Zoeller in an opinion stating, "Members of Congress do not lose their residency for voting purposes when they leave the state so that they may fulfill their duties."
Without a physical residence, challengers to his candidacy argued that Lugar could not have residency in the state, and thus, could not be an inhabitant. The commission disagreed, finding that absence of a physical residence did not disqualify Lugar from being an inhabitant.
The Indiana state constitution says "a person is not considered to have lost residence in a precinct in Indiana by reason of the person's absence on the business of (1) the state of Indiana; or (2) the United States."
And though he acknowledged the difficulty of interpreting the term "inhabitant," Long went back to the U.S. Constitution.
"This is very narrow in my mind," he said. "In my mind we get to the U.S. Constitution. It says you have to be an inhabitant in the state." That's all that needs to be decided, he said.
"I can see I'd feel a whole lot more comfortable if he had some kind of living unit here in the state," Long continued, adding that this could be an issue for voters to decide in the primary. But he resolved that there was not enough evidence to prove Lugar did not have a "presence" in the state. And a "presence," for Long, was enough to deem Lugar an inhabitant.
Indiana voter and lifelong resident David Stockdale brought one of the challenges to Lugar after also filing an unrelated challenge to former Pennsylvania Sen. Rick Santorum's placement on the Republican primary presidential ballot.
"I'm not a lawyer, all of this is very intimidating," he told CNN. Stockdale said he felt compelled to act because he suspected politicians weren't "doing what they are supposed to be doing."
"Through the news I was aware Rick Santorum didn't have enough signatures to be on the ballot, so I filed a challenge for not having the right amount of signatures," he said. "I started to look at the Lugar situation in the news [and] I don't want to be hypocritical…if the whole purpose is to keep the system free of fraud and to have candidates follow the rules, if I was going to challenge Santorum, I also had to challenge Lugar," Stockdale said.
Stockdale also took issue with Lugar's voter registration, which lists his old address in Indianapolis. "Lugar could have been committing voter fraud," Stockdale said. "I don't know. I think there's more than just this issue that needs to be addressed."
The commission also settled that question Friday when Long stated, "There are requirements of residency [to run for Senate] and the legal requirements of getting a driver's license are not connected."
Lugar, who won with 87% of the vote in 2006, will remain on the ballot for a seventh term in office, facing Mourdock in the primary.
Stockdale has not decided who he'll back in the primary or general election, but said he hoped there wouldn't be any hard feelings from the incumbent as a result of his action.
"Family and friends that I've talked to about this think I'm crazy," he said. "I have enough faith in the system (that) I would hope a senator would respect a citizen challenging them and if they're doing something right, they would appreciate the challenge to make sure they continue to do the right thing."