To be sure, FarmVille is still easily the top app in terms of daily active users, at more than 16 million compared to the second-highest app Windows Live Messenger at nearly 10 million.

FORBES: FarmVille No Longer Facebook's Top Application

The second reason why Paul has become the party's most effective messenger is that everyone across the entire ideological spectrum -- from John McCain, Rubio and The Wall Street Journal to Majority Leader Harry Reid and Attorney General Eric Holder -- is responding to him.

CNN: New leader of the GOP: Rand Paul