Ted Cruz is the toughest guy in the US Senate. Definitely presidential material IMHO.
Here he nails a very evasive Eric Holder over the constitutional permissibility of using drones to kill US citizens on American soil.
This is the interchange that got Rand Paul filibustering. For a quick synopsis, “Cruz Goes After Holder About Constitutionality Of Using Drones To Target Americans On US Soil.” CBS DC.
And about the prohibitive evils of John Brennan: “National Security Experts Warn: Reject Brennan!”
And here is the Obama interview that brought this matter to the forefront, with Barack Obama stating that there would have to be a policy for drone strikes within the United States on Citizens. “The rules outside the United States are going to be different than the rules inside the United States.”
Gulag Bound, and other key sources.