Early ratings: Fox News Channel debate second lowest for GOP this cycle

How Did Donald Trump Do Vs. Fox News GOP Debate?
How Did Donald Trump Do Vs. Fox News GOP Debate?

The first Republican presidential debate of the season without front-runner Donald Trump generated smaller viewer interest than all but one of this cycle's prior GOP gatherings, according to preliminary Nielsen estimates.

In the metered-market overnights, which represent 56 of the nation's largest markets, Fox News Channel's debate from Iowa averaged an 8.4 household rating. This is up vs. the 7.4 overnight rating for the most recent GOP debate, on Fox Business Network earlier this month, but it stands as the second lowest-rated of the six Republican gatherings this cycle.

SEE ALSO: Trump skips debate, wins on social media

Nielsen will issue total-viewer estimates later today, but it's likely that last night's debate on FNC averaged in the vicinity of 12 million viewers. By comparison, the combined viewership of CNN and MSNBC, which covered Trump's competing Iowa event last night, appears to be about 3 million or so.

Curiosity over the unpredictable Trump fueled record tune-in for the first GOP debate last summer, as Fox News Channel drew 24 million in August — the largest ever audience for a non-sports cable program — and CNN followed that up a month later with a little over 23 million. Ratings dipped for the subsequent four debates (ranging between 11.1 million and 18.2 million), though they remained higher than in years past.

The Democratic debates have rated lower, but at least some of this is due to three of them being scheduled in lower-profile timeslots on the weekend. The peak viewership came on a Tuesday last October, when CNN drew 15.8 million viewers.

Trump on Tuesday announced that he would not attend Thursday's debate over his objections to Fox News Channel's anchor and debate moderator Megyn Kelly. "Megyn Kelly's really biased against me," he said in an Instagram video that day. "She knows that. I know that. Everybody knows that. Do you really think she can be fair at a debate?"

See photos from Donald Trump's Iowa rally

He then appeared on Wednesday's edition of "The O'Reilly Factor," helping boost the show to a two-month high of 3.8 million viewers. Host Bill O'Reilly tried to persuade Trump to reconsider and attend the debate. "You are depriving people of seeing you in a forum they want to see you in," O'Reilly said to Trump before asking him point blank if he'd reconsider. "You and I had an agreement that you would not ask me that," responded Trump.

More from AOL.com:

'This is the lie that Ted's campaign is built on': Crowd boos during testy Marco Rubio exchange with Ted Cruz
Democrats get Obama pep talk, face long odds
Who won the Trump-Fox News debate showdown?