Indiana tea party activists say they don’t want to repeat their 2010 mistakes, and they’re plotting ways to make sure they pick the most conservative candidate to attempt to unseat Sen. Dick Lugar.

With state Treasurer Richard Mourdock planning to challenge Lugar in the Republican primary next year and another candidate on the horizon, the tea-party-backed effort to replace the longtime Senator is taking shape.

Tea party leaders met with Lugar in December but left unconvinced that he would begin to live up to their principles. Under the umbrella organization Hoosiers for Conservative Senate, they have begun a process to find one candidate to rally around in the May 2012 Republican primary.

“Our goal is to get the most conservative candidate, an electable candidate,” said Monica Boyer, one of the tea partyers who met with Lugar in December.

The group has planned an elaborate process to find that person. As Republicans announce their intentions to run for Senate, tea party leaders in each of the Hoosier State’s nine Congressional districts will invite them to events in their districts. At a final event tentatively planned for September near Indianapolis, the group will hold a caucus to choose its favorite candidate.

The process is designed to avoid what happened in the 2010 Senate primary, according to another tea party leader, Greg Fettig. In the race for retiring Democratic Sen. Evan Bayh’s seat, a crowded primary meant tea partyers split their votes between three candidates, allowing their least favorite candidate, former Sen. Dan Coats, to win the primary and eventually the general election. Tea partyers saw Coats, a lobbyist and former Senator, as the ultimate establishment politician.

An Indiana Republican strategist who worked on Coats’ campaign in 2010 said he was skeptical of the tea party’s efforts.

“I would say the thing about the tea party in Indiana is they are a very diverse group of folks, and the thing that made that very clear to me was there was not a central organizing figure or even one idea,” he said.

That’s something Fettig and Boyer believe they’ve had some success in combating, and they’ve talked to like-minded groups such as FreedomWorks and the Club for Growth about working together in the future. Fettig said they’ve already given advice to tea party groups in Ohio, Michigan, Oregon, Virginia, Pennsylvania and Oklahoma about uniting around a single candidate.

“We can’t prevent people from running, but we can rally around one candidate,” Fettig said.

Mourdock was first elected treasurer in 2007 and easily won re-election in 2010. He made his name nationally with a lawsuit against the administration’s bailout of Chrysler in 2009 — one of several rallying points for the tea party movement.

Mourdock is unlikely to be the only Republican who seeks the group’s support. State Sen. Mike Delph, a former staffer to Rep. Dan Burton (R-Ind.), told Roll Call he’ll focus on the job he has now and mull over other options when the state legislative session ends later this spring.

“Richard Mourdock’s announcement doesn’t change my thinking at all,” he said.

Regardless of who runs, it might take more than a tea party endorsement to take down Lugar. First elected to the Senate in 1976, Lugar had no Republican or Democratic opponent in 2006. Though he had $2.4 million on hand at the end of 2010 and has repeatedly declared his intention to run for re-election, the tea partyers still hope he will retire. They sent the Senator a letter in January warning they won’t support him and asking that he “gracefully consider retirement.”

On the other side, Democrats hope a divisive primary would benefit a Democratic nominee. Indiana Democratic Party Chairman Dan Parker said Rep. Joe Donnelly, former Rep. Brad Ellsworth and former state Health Commissioner Woody Myers have been mentioned as potential Democratic challengers.

“I think that the challenge for us is to field a strong candidate that can lay claim to the middle of the electorate because Hoosier elections are won in the middle,” Parker said.

Ellsworth, who lost to Coats by 15 points in 2010, told Roll Call he isn’t seriously pursuing another Senate bid at this point.

“It’s certainly not something I’m planning right now, but I wouldn’t rule it out either. I’m just not in the mode yet,” he said.