Donald Trump may have been the driving factor in record ratings numbers for the first two Republican primary debates of this election cycle, but he appears to have had a halo effect on the Democrats’ first gathering as well.

In preliminary estimates from Nielsen, Tuesday’s debate on CNN drew a big 15.3 million viewers — the largest-ever crowd for a Democratic debate and the sixth largest non-sports cable audience on record. Prior to last night, the highest-rated Democratic presidential primary debate on cable was CNN’s January 2008 Los Angeles debate, which averaged 8.3 million viewers. And overall, the highest-rated was ABC’s 2008 Philadelphia debate, which drew 10.7 million viewers in April of that year.

In the key news demo of adults 25-54, Tuesday night’s debate averaged 4.8 million viewers — also a record for a Democratic debate.

On the record ratings for the debate, Democratic hopeful Bernie Sanders told Variety: “Millions of Americans understand that aside from calling each other names & throwing tantrums the Republicans really don’t have anything significant to say about the real crises facing the American middle class.”

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CNN live-streamed the debate to CNN.com, its mobile apps and Apple TV, setting an all-time record for peak concurrent streams of a live news event. At 10:20 p.m. ET, usage peaked at 980,000 concurrent streams, topping the 921,000 peak concurrent streams CNN saw of its GOP debate at Reagan Library last month. By comparison, it’s estimates that NBC pulled in 1.3 million peak concurrent streams at the Super Bowl earlier this year.

The first two Republican primary debates of this cycle drew record ratings, as 24 million tuned in to Fox News for its coverage of the Cleveland debate on Aug. 6, followed by 23.06 million for CNN’s debate from Simi Valley on Sept. 16. These debates averaged about 7.5 million adults 25-54.

The Democratic debate was easily Tuesday night’s most popular series or special on Twitter, according to Nielsen Social. Roughly 8.9 million people in the U.S. saw one or more of 2.8 million tweets sent about the debate, with the biggest moment coming at 9:50 p.m. ET, when 33,500 tweets were sent following Bernie Sanders’ comment about Hilary Clinton’s emails.