What an incredible quote!
If I were on the Democrats' campaign ad team, I'd do an ad that starts with a montage of brief interviews with people who lost loved ones to terrorist attacks -- the Oklahoma City bombing, flight 107 over Lockerbie, 9/11, perhaps families of soldiers who have died in Iraq. These should be low-key, dignified, non-partisan -- brief comments about the pain they suffered. A caption would read: "These are the voices of people who have lost loved ones to terrorist attacks on America."
During this opening montage, I'd use muted colors for the background. A simple instrumental version of "The Star Spangled Banner" would play softly in the background.
Then I'd do a gradual transition to a more brightly lit scene, and show Santorum at some public speaking engagement, surrounded by lights and cameras and reporters.
Now we segue into a tape of Santorum speaking. (There should be a caption, "Senator Rick Santorum speaks on the importance of a constitutional amendment to ban gay marriage", to make it clear what's going on.) Meanwhile, the background music gets fainter and fainter, until (as Santorum reaches the part, "Isn't that the ultimate homeland security...?") the music becomes inaudible and only Santorum's voice can be heard.
As Santorum finishes, fade in a very brief montage of Santorum shaking hands with or embracing Bush and other top Republicans. (This can be tailored, state to state, to include Santorum standing next to or with his arm draped around that state's Republican candidates for office.) Then fade the picture out slowly to a completely black screen.
Now the closing line appears, written against the black background, with absolutely no sound: "Is this the party you want in charge of national security?"