IMO, there is no group more willing to destroy America than Liberals. Pelosi, Murtha, Boxer, Feinstein, Kennedy, Reid, Feingold, Schumer, and the rest have absolutely no regard for this nation or our security. No Liberal met a terrorist they didn’t feel sorry for. They hate the US military and their mission. Therefore, what better group than Liberals for our enemies to recruit from. In fact, one could say that Liberals and Islamic fanatics are allies in their quest to destroy America.
Consider that modern radical islam uses the same play book as modern liberal America: The Communist Manifesto. Radical islam and liberals both recruit from circles that consider themselves to be victims of the rest of the world, and give them a way to vent their rage by taking down those identified as the "ruling elite".