The Republican candidates' debate on Fox News Channel attracted 24 million viewers, more than double the prior record for a presidential primary forum, with social media data suggesting combative billionaire Donald Trump was the main attraction.

Viewership for the raucous 10-way debate was the highest nonsports telecast in cable history, according to Nielsen data provided by Fox.

Republicans will mostly welcome the attention to mainstream candidates like Marco Rubio, the U.S. senator from Florida, and Jeb Bush, the former Florida governor, as they try to prevent a Democrat winning the White House in November 2016 for the third time in a row.