Sen. Lugar has not lost an election in 38 years to be exact. But in 2012, the six-term Republican incumbent finds himself a tea party target.
"I'll be a different kind of senator, an unapologetic conservative," said Indiana treasurer Richard Mourdock.
Mourdock is telling Republican voters that Lugar has lost his conservative values.
"How else to explain his support for amnesty, Obama's liberal supreme court choices, even his vote to bail out Greece, that's out of touch," he said.
But the 80-year-old incumbent -- the most senior Senate Republican and ranking member on the Foreign Relations Committee -- is not giving up.
Lugar phone banks have called over a million Indiana Republicans, many if not most of whom are likely to have voted for the senator during his six previous election campaigns.
"We need them to go out tomorrow and support Dick Lugar and remember again what he's done in the past," said Celina Weatherwax, Lugar supporter.
"He served us well in the beginning but his views are less and less conservative, and it's not resonated with Hoosier voters," said Suzy Barnhart, Mourdock supporter.
Mourdock is backed by most of Indiana's numerous tea party units, and supporters in St. John are outraged by Lugar's willingness to negotiate and find middle ground with Democrats.
"We don't need Republicans that are voting like Democrats," said John Gordon, Mourdock supporter.
"Being able to reach across the aisle is a gift but more importantly is being able to listen. And we have a lot of politicians and a lot of Americans who just aren't listening right now," said Douglas Luke, Lugar supporter.
Popular Governor Mitch Daniels was featured in an ad for Lugar during the campaign's final week. Mourdock supporters call it a last gasp by the state's Republican establishment.
"The truth can take a beating at campaign time and this year it's Dick Lugar on the receiving end," said Daniels in the ad.
"Dick Lugar is the establishment," said Barnhart. "Richard Mourdock is 'We the people.' And we have the grassroots support."
Most pre-election surveys have indicated the race is very close, and at least one reported that Mourdock was leading Lugar.