Up against stiff competition from two of television’s most popular series, the biggest drama of the fall — “The Republican Primary Debate” — drew more monster ratings on Tuesday night.

Nielsen estimates that the fifth and final Republican debate of the year, and the first held in more than a month, averaged 18.04 million viewers on CNN. This makes it the third most-watched presidential primary debate ever, behind only the two summer GOP debates that kicked off the 2016 election cycle. And it’s more than 2 1/2 times what a comparable GOP debate drew on Fox News Channel at this time four years ago (6.7 million).

The first two Republican debates of the 2016 election cycle drew record ratings for Fox News Channel (23.997 million on Aug. 6) and CNN (23.056 million on Sept. 16). Viewership dropped off for debates on CNBC on Oct. 28 (14.005 million) and Fox Business Network on Nov. 10 (13.454 million), but these were all-time ratings highs for these stations.

Viewership then went back up last night as action returned to CNN — even though Tuesday’s debate faced some stiff competition on the broadcast networks, including the season finale of TV’s most popular reality show (NBC’s “The Voice”) and the year’s finale episode of TV’s most-watched drama (CBS’ “NCIS”).

If you include the Oct. 13 Democratic debate that drew 15.79 million viewers on CNN, the network has now drawn three of the year’s four most-watched presidential primary debates.

In the key news demo of adults 25-54, the debate averaged roughly 5.6 million viewers (a 4.7 rating). This also ranks third, behind the Fox News Channel debate from Cleveland in August (6.64 million demo viewers) and the first CNN debate from Simi Valley, Calif., in September (5.98 million).

CNN live streamed Tuesday’s debate to CNN.com, its mobile apps and connected TVs, earning at least 3.1 million live streams. The event reached peak usage at 9:45 p.m. ET with 815,000 concurrent streams. The record high for peak concurrent streams remains the more than 1.4 million generated by the Fox Business Network GOP debate last month.

Twitter was busy during the CNN Republican Debate, during which 8.5 million people in the U.S. saw one or more of the 2.4 million tweets that were sent, according to Nielsen. The top mentioned candidate of the night was Donald Trump, with “Trump” mentioned in 522,000 tweets.

The second most popular television program on Twitter, “The Voice,” attracted 206,000 tweets, which were seen by a unique audience of 2.93 million people.

Last night’s 150-minute debate, dominated by Republican front-runner Donald Trump and his chief rivals Jeb Bush, Ted Cruz and Marco Rubio, was held at the Venetian hotel in Las Vegas and moderated by CNN’s Wolf Blitzer. It focused primarily on national security and the war against ISIS.

ABC will carry the third Democratic debate of the 2016 election cycle on Saturday from Manchester, N.H. The next scheduled Republican get-together is set for Jan. 14 from Charleston, S.C., on Fox Business Network.