INDIANAPOLIS -- Sen. Richard Lugar sounded wistful in his gratitude when he thanked supporters packed in the skybox of the Indiana Pacers' home court, as though he could see the approaching end of a political career that has spanned nearly half a century.
"I thank all of you, the 50 or 60 of you who are co-sponsors of the rally. We appreciate very much your willingness to put your own names on the line and be helpful in bringing together this assembly," said the 80-year-old Indiana Republican who was first elected to the Senate in 1976.
That characteristically understated demeanor has endeared Lugar to generations of Hoosier voters. It belies the fierce battle in Republican circles over whether to retire him now or give him six more years in Washington.
Lugar and Utah's Orrin Hatch, 78 and sent to Capitol Hill in the same year as Lugar, are tea partyers' top Senate Republican targets for defeat this year, portrayed as old bulls out of touch with today's conservatives. They are the GOP's two most senior members in the Senate.
Both have come out swinging, a lesson learned when Hatch's fellow Utah senator, Robert Bennett, had his re-election bid derailed two years ago by the fledgling tea party movement in the state GOP's nominating convention.
Hatch has shored up his support, furiously courting delegates to this year's convention on April 21. He has emphasized his seniority and covered his flank with more conservative stances and votes.
Lugar also started early, hiring a full-time campaign manager in the fall of 2010. He built an extensive network of campaign volunteers and by the first of this year had amassed a 10-1 cash advantage over his tea party challenger, state Treasurer Richard Mourdock.
Lugar, however, has had to play a frantic defense heading into the May 8 primary after tea partyers, joined by Democrats, turned the incumbent's residency outside the state into a dominant campaign issue.
He fumbled questions about the address on his driver's license: an Indianapolis home he sold in 1977. He had to switch his voter ID to his farm in Indianapolis after the local election board ruled last month that he couldn't vote using the 1977 address. Lugar, who owns a home in Virginia, also repaid the U.S. Treasury $14,700 last month that his Senate office paid for his hotel stays in Indiana.
"That's a self-inflicted wound. It just doesn't look good symbolically," said Margaret Ferguson, who heads the political science department at Indiana University-Purdue University Indianapolis. "Things that have been brushed aside now carry some momentum that they would not have in the past."
Conservatives have rallied around Mourdock, a geologist and quiet campaigner who three years ago challenged the Chrysler bankruptcy terms in the U.S. Supreme Court. The Club For Growth, National Rifle Association, Citizens United, Hoosiers for Conservative Senate and FreedomWorks, a tea party umbrella group, have endorsed him.
The Club for Growth purchased more than $250,000 in airtime over the past two weeks for anti-Lugar ads after spending $160,000 against him last year. FreedomWorks has spent $100,000 in Indiana.
"Lugar is still in control of this race, but it's tight, much tighter than it was six months ago," said Andy Klingenstein, one of a trio of former aides who formed the Indiana Values super political action committee to battle on Lugar's behalf.
Lugar's power in Indiana Republican circles is legend, multiplied by generations of aides and operatives who cut their teeth with him in the 1960s when he was mayor of Indianapolis. He's been insulated from serious challenges within his own party and even Democrats have considered him invincible, choosing in 2006 not to field a challenger.
But a strong anti-incumbent mood and pressure from the right to define who really is a conservative have forced the well-funded Lugar to turn to super PACs like Klingenstein's, which is airing ads attacking Murdock.
Monica Boyer, one of the leaders of Hoosiers for Conservative Senate, said she, like most other Indiana tea partyers, had always voted for Lugar because "he had an `R' in front of his name."
The tipping point, she said, was when Lugar voted to confirm President Barack Obama's Supreme Court nominees, Sonia Sotomayor and Elena Kagan. That was a "hard wake-up call," she said, that spurred tea partyers to dig deeper into Lugar's voting record. There, she said, they discovered votes for an assault weapons ban and other moderate stances that have led critics to say Lugar is Obama's "favorite Republican."
"We learned how to use the roll call system. That's probably his worst nightmare right now," Boyer said.
The tightening of the GOP race has left Democrats giddy. Pushing their own candidate, U.S. Rep. Joe Donnelly, they look at what once was considered a safe Senate seat for Republicans as now in play in the general election.
Hatch, who needs 60 percent of the state GOP convention delegates to win on the first ballot, appears to be faring better in Utah. Supporters have spent more than a year emphasizing the importance of his seniority as the top Republican on the tax-writing Senate Finance Committee and his influence on federal land issues and the next round of military base closings.
"I'm in a position that benefits Utah in a fantastic way," Hatch said. "This going to be my last term. I'm committed to that. But it's going to be the best six years you've seen."
That argument has played well with state GOP convention delegates, some of whom said during recent caucus meetings they feared having two first-term senators from the state. It also was underscored in an endorsement by leading Republican presidential contender Mitt Romney, who is extremely popular among Utah Republicans.
Dan Liljenquist, a former state senator who seems to be Hatch's strongest challenger, has tried minimize the seniority issue by highlighting the increased debt and spending on benefit programs during Hatch's tenure.
"Is seniority so important that we feel forced to make the same decisions for the same people that got us into this mess? For me, leadership trumps seniority every time. There is a time for new leadership, and that time is now," Liljenquist said.
FreedomWorks director Russ Walker said his group will continue to work for Hatch's "retirement" after spending nearly $650,000 leading up to the March caucus meetings.
But he acknowledged it isn't as easy to paint differences between Hatch and his opponents as it was in 2010, when Bennett was being hammered for supporting the Troubled Assets Relief Program and had co-sponsored a bipartisan health care overhaul.
"It's a little more challenging this cycle because everybody is saying the same things," Walker said. "We have to define the differences."
For Lugar, those differences may boil down to whether Indiana voters think he's conservative enough.
Polling shows Mourdock closing as money flows into the race from both sides. Klingenstein's pro-Lugar group plans to spend upward of $1 million on the race, and Walker said FreedomWorks plans to expand its opposition to Lugar. Another pro-Lugar super PAC, Hoosiers for Economic Growth, is raising $1.75 million in its effort.
Gov. Mitch Daniels, a Lugar protege who has headlined fundraisers for him in Indiana and Washington, said it's been so long since Lugar has had a competitive race that many voters don't have much of an image of him. That has hurt Lugar's efforts to defuse questions about his residency and roots in the state, according to Daniels.
"He was in nothing but tough races, until he wasn't," Daniels said. "There's probably a couple of generations of voters that don't have all the information that people did back then."
Associated Press writer Josh Loftin in Salt Lake City contributed to this report.