INDIANAPOLIS — Timing is everything, especially in a political campaign. Come out negative too early and you can turn off voters. Wait too long to try to brand your opponent and you may find it hard to get your message across.

That seems to be the case with the campaign of six-term Sen. Richard Lugar, whose efforts to paint tea party-backed state Treasurer Richard Mourdock as “untrustworthy” last week had all the markings of a desperate attempt to toss anything and everything at Mourdock to see what might stick less than two weeks before the vote that could end Lugar’s political career.

First came the Lugar campaign’s cryptic promise of “critical” new information about Mourdock that would prove he wasn’t a conservative. Then came the ballyhooed press conference at the Marott apartments in Indianapolis, where Lugar spokesman Andy Fisher and Lugar supporter Larry MacIntyre pointed to a 1992 candidate questionnaire on which Mourdock supported the “Fairness Doctrine” and declined to say whether he would sanction illegal immigrants.

They also rolled out a litany of previous complaints they have outlined in attack ads that have run across the state since March.

Even with a room packed with print and broadcast reporters, the alleged game-changer got little play beyond some tweets and blog posts. The reaction? Nothing to see here. Move along.

The campaign’s effort to make a dent in Mourdock this close to the primary begs the question: Has Lugar waited too long to try to brand his opponent?

“I think it’s on time because a lot of people are making their decision now,” said Lugar spokesman Andy Fisher.

There’s plenty of support for Fisher’s theory that the most important battle is fought just before the election. The heaviest spending in this campaign has come in the final two weeks, with the two campaigns and outside interest groups supporting them laying out a combined $1.55 million for broadcast ads through May 8.

But the lack of attention paid to the Lugar announcement may illustrate the biggest challenge the senator faces: This race has never been about defining Mourdock. It’s about Lugar, said former Indiana Democratic Party chairwoman Ann DeLaney.

“That was the shot heard round the block,” DeLaney mocked, referring to the Lugar campaign’s effort to paint Mourdock as untrustworthy last week.

Mourdock has already been successfully branded as well to the right of the 36-year incumbent, thanks to supporters who started firming up the public’s image of the candidate early on.

Lugar’s team was still deciding what to do with Mourdock in March when leaders from national tea party organizer FreedomWorks and Hoosiers for Conservative Senate, Indiana’s tea party umbrella group, met during a training session in Westfield. The organizers urged their troops to begin telling Hoosiers about Mourdock before their opponents beat them to the punch.

As they departed the home of Hoosier for Conservative Senate Greg Fettig, they left behind the brochures tying Lugar to Obama and picked up the stack with a smiling shot of Mourdock. By that point, they had moved from the “Retire Lugar” message to the “Elect Mourdock” one.

Meanwhile, 36 years of successful branding has labeled Lugar as a bipartisan operator with deep roots in Washington, a no-no among tea partyers and conservatives.

That view was reinforced Friday when the Republican Party’s 2008 presidential ticket split its endorsements in the Senate race. The more moderate Sen. John McCain cut a radio spot endorsing Lugar, while tea party icon Sarah Palin announced she was backing Mourdock.

With just over a week to go, the Lugar camp has shifted away from its barrage of attacks to a more positive message from surrogates. Gov. Mitch Daniels has cut a pair of ads for Lugar touting his experience and ability to get things done within both the figuratively and literally labyrinthine corridors of the Capitol.

They can only hope this message finds a more receptive audience.