LOS ANGELES — NBC says round two of the Democratic presidential debate was the party’s most-watched ever.

Based on Nielsen figures out Friday, the event including early front-runners Joe Biden and Bernie Sanders averaged 18.1 million viewers across NBC, MSNBC and Telemundo.

That topped the previous Democratic debate audience high of 15.5 million for an October 2015 event, which included eventual nominee Hillary Clinton.

Neither approached the audience for the first 2016 GOP primary debate, with newcomer Donald Trump driving curiosity. It drew nearly 24 million viewers on Fox News Channel.

This week’s pair of Democratic debates, the first of the 2020 campaign, split a field of 20 contenders into two groups.

A headline-making exchange Thursday involved former Vice President Biden and Sen. Kamala Harris, who sparred over Biden’s civil rights record.