04/05/2012 04:49 pm ET Updated Apr 05, 2012

Dick Lugar, Indiana Sen., Faces Close Republican Primary: Poll

Veteran Hoosier Sen. Dick Lugar (R-Ind.) is in a tough battle to win his primary contest against a Tea Party challenger, a poll released Thursday said.

The Howey/DePauw Indiana Battleground Poll showed Lugar leading Indiana state Treasurer Richard Mourdock by just 45 percent to 37 percent.

The result prompted Howey Politics Indiana, which co-sponsored the survey, to move the contest from "lean" Lugar to a toss-up.

Lugar has been under attack not just by Mourdock, but by right-wing groups including the Club for Growth and the Tea Party's FreedomWorks. His campaign downplayed the startling numbers.

"This poll shows what we have been saying all along -- Hoosier voters are rejecting Richard Mourdock's use of outside special interest groups' money to run his all-negative campaign against Dick Lugar," said a statement from campaign spokesman Andy Fisher. "The group that conducted this poll notes in the Howey Report that it was taken as outside money poured in to attack Dick Lugar. Also, the Lugar campaign has gained ground in the 10 days since the poll was taken."

Fisher also found solace in a low name-recognition rate for Mourdock.

"As the poll says -- most people don't know Richard Mourdock," Fisher said. "As we find in our daily calls to Hoosier primary voters -- which we have made more than a million -- once they know Richard Mourdock, they won't choose Richard Mourdock."