After dashing fellow Republicans' hopes of extending surveillance program, Ky. senator holds fast in media blitz.
Clinton is Fiorina's foil and chief raison d'etre in her long-shot bid for the GOP nomination.
Paul has become a frequent target for GOP presidential hopefuls who have painted his foreign policy as weak – and even dangerous.
After winning 11 states in 2012, the former Pennsylvania senator finds himself an underdog for a second time.
He said the more military-minded members of his party have been "wrong for 20 years."
Groups argue that Bush and his Right to Rise PAC may be "engaged in knowing and willful violations of federal campaign finance laws."
When asked if Bush is conservative enough to be the Republican nominee, Paul said, "I doubt it."
On the itinerary: Iowa, South Carolina, New Hampshire.
Last time around, a black voter exodus helped torpedo Clinton's run. This time around, she's counting on them to deliver a win.
The Simpsons, The Princess Bride and Reagan make campaign trail cameos.