Senate contracting panel leader targeted in six-figure ad buy

Crossroads GPS is hitting Sen. Claire McCaskill, D-Mo., with a new six-figure ad buy that attacks the senator over Medicare and taxes.

"Claire claims to protect Medicare, but she voted to cut Medicare spending half a trillion dollars by supporting Obamacare," says the narrator of the ad.

Crossroads GPS is spending $300,000 to air the ad statewide over a two-week period.

More than any of her GOP opponents, attacks from outside groups have been McCaskill's biggest worry in the race so far. In her first TV ad, she directly pushed back against the outside groups that have targeted her on the airwaves.