The results are a dramatic change from a similar Howey poll taken just five weeks ago. At the end of march, Lugar lead Mourdock by seven percent.
Experts say while the numbers could change by election day, a Mourdock win could change the game in the general election against candidate Joe Donnelly.
"What people should remember is that six years ago, Democrats didn't even run anybody against Dick Lugar," says Andy Downs of IPFW's Mike Downs Center for Indiana Politics. "They knew[Lugar] had a lot of support among moderates and even among some democrats. Mourdock won't have as much of that."