JEFFERSONVILLE, Indiana (Reuters) - Indiana Republicans last spring spurned long-time Senator Richard Lugar for a more conservative candidate, but now supporters of the soft-spoken moderate may tip the balance in the race that could determine which party controls the U.S. Senate.

Indiana Republican U.S. Senate candidate Richard Mourdock, speaks with volunteers at the Republican “Victory Center” in Jeffersonville, Indiana October 3, 2012. Indiana Republicans last spring spurned long-time Senator Richard Lugar for a more conservative candidate, but now supporters of the soft-spoken moderate may tip the balance in the race that could determine which party controls the U.S. Senate. Picture taken October 3, 2012. REUTERS/Nick Carey

Republican Richard Mourdock, the state treasurer, and his Democratic opponent, Congressman Joe Donnelly, are wooing not just independent voters but disaffected and angry “Lugar Republicans.”

“Dick Lugar is a statesman,” said Karl Stein, 63, a Republican, as he was walking the dog near Indianapolis. “I don’t like the way he was thrown under the bus after all he’s done for Indiana.”

Republicans need a net gain of four seats to win a Senate majority, or three if Republican Mitt Romney wins the White House because his vice president would cast tie-breaking Senate votes. Republicans began 2012 in a strong position, with Democrats defending 23 of 33 seats up for election, but have suffered some self-inflicted wounds.

In Missouri, Republican candidate Todd Akin prompted an uproar by saying women’s bodies have defenses against pregnancy after “legitimate rape,” and now trails in the race.

Republican candidates also are facing tougher-than-expected contests in Arizona and North Dakota as well as Indiana.

Mourdock has been hit by Democrats attacking his “extreme” Tea Party movement views - lower taxes, fewer regulations and massive spending cuts - plus his televised remarks after the primary that “bipartisanship ought to consist of Democrats coming to the Republican point of view.”

“It wasn’t easy for a lot of Hoosiers to see Lugar defeated after a slashing campaign,” said Marjorie Hershey, a politics professor at the University of Indiana, using the term Indiana natives call themselves. “Mourdock didn’t help himself after the primary by taking a very hard line.”

‘FAILED AND FAILED AND FAILED’

A September Howey-DePauw poll put Donnelly up by 2 points over Mourdock, 40 to 38 percent, with 7 percent for a Libertarian candidate.

Mourdock’s strong conservative base enabled him to defeat Lugar, who was first elected in 1976, in the Republican primary contest to choose a candidate.

Lugar was re-elected repeatedly in November general elections with the help of Democrats and independents who admired his record of bipartisanship and foreign policy expertise that included helping to decommission some of the nuclear weapons of the former Soviet Union.

“It’s always tough when your man gets beat,” said Mike Missi, 58, a volunteer for the Mourdock campaign who has encountered a number of unhappy Lugar supporters.

“But if they’re true Republicans they need to vote for Mourdock,” added Missi, who was waiting for his candidate to speak to volunteers in the picturesque town of Jeffersonville on Wednesday. “And they will if they care about this country.”

Mourdock, gently spoken and affable, made brief remarks about the need to “get America running again. We’ve tried the Democratic way and it’s failed and failed and failed.”

In an interview, Mourdock said he was “willing to work with anyone who wants to make government more efficient” and said his opponent is a liberal “claiming to be a moderate.”

He said he is reaching out to Lugar supporters, but “the bigger prize is independent voters.”

Also this week, Donnelly spoke to seniors at a healthcare center in Evansville, in the southwestern toe of Indiana, promising to “protect and strengthen Medicare” - which provides health insurance for seniors and those with disabilities.

‘AMERICAN HERO’

Donnelly, like Mourdock cheerful and soft-spoken, introduces himself to seniors with a simple: “Hi, I’m Joe.”

He calls Lugar “an American hero” and says he will court Lugar supporters by telling them the same issues matter to him that matter to Lugar. Donnelly also stresses that he worked with Lugar on a bailout for the auto industry after the 2008 financial crash, which Mourdock opposed.

“Donnelly has a very good chance of winning,” said Brian Vargus, a political scientist at Indiana University-Purdue University Indianapolis. “But he has to maintain his momentum.”

One factor favoring Donnelly is that Lugar has stayed away, telling an Indianapolis blogger in September: “I have not been a factor in the campaign and I do not intend to do so.”

“I am not concerned about Lugar supporters voting for Donnelly,” said Greg Fettig, one of the leaders of Hoosiers for a Conservative Senate, which spearheaded the Tea Party campaign to help Mourdock win the primary. “Real Republicans just aren’t going to vote for a Democrat.”

But Stein, the Lugar admirer, is not so sure, adding that he was still undecided on his vote. “As of now I can tell you it won’t be Mourdock,” he said. A Libertarian candidate is also on the ballot along with the Democrat and the Republican. (Editing by Greg McCune and Vicki Allen)