Last night's CNN GOP debate from the Reagan Library ranked as the fourth most-watched primary debate on cable, with 4,000,000 million total viewers. The 90-minute debate ranked #3 in the A25-54 demo in cable, with 1,400,000 million viewers. The numbers are based on Nielsen Fast Nationals, Live + SD.

The debate gives CNN the top four highest rated cable debates in this primary cycle in total viewers.