ADVERTISEMENT
The ad, which is running statewide on radio and has $20,000 behind it, comes a week after a pro-Mourdock super-PAC blasted Rep. Joe DonnellyJoe DonnellyOvernight Energy: Fight over miners' benefits risks shutdown | Flint aid crosses finish line in House House approves funding bill, but fate in Senate unclear Messer eyes challenging Donnelly for Indiana Senate seat MORE (D-Ind.), Mourdock's opponent, for being a "rubber stamp" for President Obama.

The Hill rates the race a "toss-up."

Listen to the ad: