WASHINGTON (Reuters) - One of the last members of the Senate's "old guard," Republican Richard Lugar, stressed his conservative credentials on Wednesday in a debate with a primary opponent who suggested he was out of touch with Indiana voters.
Lugar, 80, who has faced token opposition in his five previous re-election campaigns, is in an unexpectedly tight race with Indiana state Treasurer Richard Mourdock, who is backed by the conservative, populist Tea Party movement.
Some recent polls show Lugar leading Mourdock by single digits ahead of the May 8 primary.
The contest is seen as a test of the Tea Party's potential impact on the 2012 elections. The movement was instrumental in galvanizing a populist surge that gave Republicans control of the U.S. House of Representatives and many statehouses in 2010.
Tea Party challengers also were able to oust more moderate Republicans in primary challenges two years ago, a trend that Mourdock, a 60-year-old former geologist, hopes to continue in the conservative Midwestern state.
In a live televised debate in Indianapolis, the only one scheduled, Lugar touted his Indiana roots and a 35-year conservative voting record and praised House Budget Committee Chairman Paul Ryan, a lightning rod for Democratic attacks.
"I have been managing our family farm over 50 years," Lugar said. "Thinking about corn and soybean prices about every day ... These are the conservative elements of my life and they are expressed in my votes."
In a reference to controversy over Lugar's residency - he has not maintained a residence in Indiana since 1977 - Mourdock said he would not move from the state if elected.
"The first thing I am going to do to represent Hoosiers is to be in touch with them," Mourdock said, using the folksy term for a resident of Indiana.
"I am proud to call this state home ... It is a place, that if I have the privilege of serving as your U.S. senator, I'm not moving from," said Mourdock, who has tried to paint Lugar as the consummate Washington insider.
Lugar, one of the Senate's two longest-serving Republicans, recently reimbursed $14,700 in hotel fees improperly billed to taxpayers, and switched his voter ID to his Indiana farm after an election board said he couldn't vote using his 1977 address.
Lugar did not address the residency flap during a debate that neither candidate seemed to dominate.
Mourdock conceded he didn't know as much about foreign policy as Lugar, who has chaired the Senate Foreign Relations Committee and would be in position to do so again should he be re-elected and Republicans take control of the Senate.
Jennifer Duffy, senior editor at Cook Political Report, a prominent online newsletter, put Lugar's chances of winning the primary at 50-50.
"He has handed (opponents) a pretty potent issue" with the residency issue, Duffy said, adding that Lugar's pragmatic and bipartisan approach may not be appreciated as much on the more polarized U.S. political stage.
"Lugar is definitely one of the remaining members of what I refer to as the old guard," Duffy said, referring to a group of senators who worked across party lines. "It used to be that 'playing well with others' was a highly valued quality in someone. It's not anymore."
Conservative critics also have attacked Lugar for voting to raise the U.S. debt limit, support the 2008 bank bailouts and confirm President Barack Obama's Supreme Court appointees, and have described the senator as Obama's favorite Republican.
Lugar's supporters point out he opposed Obama's healthcare restructuring legislation and the economic stimulus package, both of which are highly unpopular among conservatives.
The winner of the Republican primary will face U.S. Representative Joe Donnelly in the general election in November. Six years ago, Lugar was considered so invincible that he didn't have a Democratic challenger.
Reporting By Susan Cornwell; Editing by Paul Simao