Dick Lugar spokesman says national tea party makes Richard Mourdock competitive in Indiana

— -- INDIANAPOLIS--In his more than 35 years in the Senate, Indiana Republican Dick Lugar has never had to campaign like this.

Since he was first elected in 1976, Lugar has not once been forced to run a primary campaign and get his Republican supporters to the polls. The last time he ran six years ago, he didn't even have a Democratic challenger.

That's all changed this year, thanks to a May 8 primary challenge from Richard Mourdock, the state treasurer who is running to Lugar's right with tea-party backing. Mourduck argues that Lugar has lost sight of the conservative values his state's voters prefer.

Andy Fisher, a Lugar spokesman, told Yahoo News in an interview Tuesday that the campaign views Mourdock, first elected treasurer in 2006, as an opportunist whose campaign is made possible only by national tea party and outsider groups.

"Treasurer Mourdock was never able to raise money in the state of Indiana and have an organization here in Indiana," Fisher said. "He really had to pledge fidelity to the positions of some national groups--particularly Club for Growth and FreedomWorks and some others--so that they would come in to buy the ads and run his campaign for him."

Fisher added that if this campaign had taken place before the time of super PACs (political action committees that can raise unlimited donations, including from corporations) the Lugar campaign would be enjoying a "terrific advantage, and there wouldn't be a race."

Fisher differentiated between national tea party influence and county tea party groups--some of which are supporting the incumbent, he said. "It's national money."

Mourdock has openly welcomed the tea party label. He told Yahoo News Monday that when he begins meetings with tea party backers, he always says: "I have only three words for you: God. Bless. You." Mourdock said that's because "the tea party's bringing the Republican party back to a more conservative base."

( Watch Yahoo News' interview with Richard Mourdock here.)

Mourdock is one of several tea party challengers running this year in primaries against establishment Republicans--including Dan Liljenquist, who pushed Utah Sen. Orrin Hatch into a primary race at Saturday's state Republican convention.

Like Hatch, Lugar is in one of the toughest electoral fights of his life.

The Lugar campaign is focused on getting absentee ballots to voters (early voting began on April 9), phone banking and direct mail, instead of the traditional television-ad-heavy campaign the Senate veteran used to run in the absence of challengers.

"This is, by far, the most expansive volunteer force that we've had, the most money we've had and the most details in terms of all the voter I.D., get-out-the-vote efforts," Fisher said.

Lugar will likely do well in rural and less densely populated areas not covered by the major media markets Mourdock is using to increase exposure to his campaign, Fisher said.

Mourdock is using the airwaves, in part, to attack Lugar, accusing the senator of becoming a moderate, highlighting Lugar's votes in support of Supreme Court nominees Elena Kagan and Sonia Sotomayor, and pointing to the "Obama's favorite Republican" label MSNBC placed on the senator and other actions Lugar has taken in Congress, all of which appear in a new ad Mourdock's campaign began airing Tuesday.