The Republican primary fight to succeed Sen. Jim Bunning (R-KY) has heated up, with Kentucky Secretary of State Trey Grayson hitting GOP frontrunner Rand Paul hard on the causes of 9/11. Grayson has come out with an ad splicing together comments by Paul, his father Ron Paul, and the Rev. Jeremiah Wright about blowback, U.S. foreign policy, and 9/11. The Washington Post‘s Chris Cillizza notes that whatever else can be said for the theory, blowback is “a stone-cold loser in a Republican primary anywhere in the country but particularly in a state as conservative-leaning as Kentucky.”

Rand Paul immediately struck back with an ad of his own recalling where he was on 9/11, placing the blame for the attacks squarely at the feet of the terrorists “who killed 3,000 innocents,” and blasting a “desperate Trey Grayson.” Paul concludes the ad by looking at the camera and saying, “Trey Grayson, your shameful TV ad is a lie and it dishonors you.”

I profiled Rand Paul in the May issue of Reason and have written about him for the main site. He has been extremely careful during this Senate campaign to use a different tone in discussing foreign policy than his father (even when the substance is the same, though it is sometimes different). The comments in Grayson’s ad all appear to be taken from when the younger Paul was a surrogate for his father during the 2008 presidential race. It is clear that Grayson views foreign policy and 9/11 as the best ways to score what would now be an upset in the Republican primary, with hawks nationally taking notice that they have six weeks to keep a savvy Ron Paul Republican from winning a senatorial nomination.