CNN was the cable news leader in primetime Sunday behind its Democratic debate and the premiere of six-part docuseries “Race for the White House,” which became the network’s highest-rated original series telecast ever.

According to preliminary Nielsen estimates, CNN’s Democratic primary debate from Flint, Michigan averaged 5.5 million viewers from 8 to 10 p.m., including 1.79 million adults 25-54. In both categories, it ranks sixth among seven Dem debates thus far this election cycle. Sunday’s debate, anchored by Anderson Cooper, focused primarily on the water crisis in Flint.

At 10 p.m. ET, “Race for the White House” debuted with 2.56 million viewers, including 885,000 adults 25-54. This represents the best CNN Original Series premiere ever, and also out-rates every other original-series telecast on the network.

Narrated by Kevin Spacey and using rare archival footage, interviews and stylized dramatizations, each episode tells the story of one iconic campaign for President of the United States. Last night’s premiere was Kennedy/Nixon; next week’s will be Lincoln/Douglas.

Overall for the night, CNN towered over the cable news competition. In fact, it drew more than three times the combined Fox News-MSNBC competition from 8-11 p.m. in both adults 25-54 (1.49 million) and total viewers (4.52 million).

Sunday was another strong day of streaming viewership for CNN, which saw 8.2 million video starts and 1.2 million total live streams across the Web, app, Apple TV and Roku. And on the social media front, 5.9 million people in the U.S. saw one or more of the 923,000 tweets about the debate, with the most tweeted minute coming at 9:42 p.m. ET when 7,000 tweets were send after Hillary Clinton and Bernie Sanders discussed climate change.