Luntz Focus Group Picks Big Debate Winner, Laments 'Sophomoric' Insults

EXCLUSIVE PICS: Behind the Scenes Before the Fox News GOP Debate

Last night's Fox News Republican primary debate attracted 16.9 million viewers, according to early Nielsen ratings, making it the highest-rated debate of the year so far.

The event, moderated by Bret Baier, Chris Wallace and Megyn Kelly, was also the fourth-highest primary debate in history, and the second highest-rated telecast in FNC history.

5.5 million of those viewers were between 25-54 years old.

The debate also broke digital records, attracting 2.4 million viewers and peaking at nearly 1.5 million, making it the most watched live-stream primary event ever!

7.4 million people tuned into a special post-debate 'O'Reilly Factor,' making it that show's highest-rated telecast of the year.

Debate Highlights: Cruz, Rubio & Kasich Will Support Trump If He Wins

O'Reilly Interviews Trump, Rubio, Cruz and Kasich After the GOP Debate

Krauthammer Reacts to GOP Debate: 'It Was a Complete Assault on Trump'