A group tied to former White House political director Karl Rove launched attack ads against Democratic Senate candidate Joe Donnelly last week.  Now Donnelly is fighting back by attacking Republican Richard Mourdock.  The Tea Party is a big reason why Mourdock defeated Dick Lugar in the GOP primary.  Donnelly now hopes to use Mourdock’s Tea Party ties against him.

The TV ad that hits the air tomorrow is paid for by Indiana Democrats but approved by Joe Donnelly who earlier this week acknowledged a need to fight back against outside interests.  “I’m sure I’ll never be able to match them dollar for dollar,” he said.

The ad is an effort to paint Richard Mourdock as an extremist.  It says, in part, “He says Social Security is unconstitutional, wants to cut medicare by $200 billion.”

“It’s important for our campaign to demonstrate that Richard Mourdock is full of those Tea Party extreme ideas,” says Donnelly campaign spokesperson Elizabeth Shappell.  Mourdock has welcomed Tea Party support but tries to avoid the Tea Party label.  Donnelly wants it to stick.

That’s where state GOP chairman Eric Holcomb comes in.  He’s trying to convince voters that Mourdock is a mainstream Republican without turning away from the Tea Party.  “The Tea Party has the exact same thing in mind about the country’s future as do most Hoosiers,” says Holcomb, “and that is we cannot continue to spend our way out of this mess.”  But the first ad from one of the candidates is based on the belief that moderate voters will make the biggest difference come November.

Richard Mourdock, meantime, was in Fort Wayne today appearing with Congressman Marlin Stutzman.  Call it a Mourdock mainstream moment. It’s one of a series of appearances designed to show that Mourdock has the support of top level Republicans.