Staten Island Republican Michael Grimm is using an endorsement from Rudy Giuliani in his latest TV ad. The former New York City mayor says Grimm "knows first-hand the destruction caused by terrorists."

The ad comes on the heels of a TV spot released Michael Allegretti, Grimm's rival for the nod to face Rep. Mike McMahon (D-N.Y.). Allegretti's spot focused on the economy, and featured several shots of downtrodden-looking residents staring forlornly at the camera.

New York's primary is Sept. 14. Grimm is considered the frontrunner, having been backed by Giuliani and other high-profile Republicans such as Sarah Palin and Sen. John McCain (R-Ariz.).

Allegretti's spot was released last Friday.