CNN's broadcast of the second night of Democratic presidential debates this week attracted 10.7 million viewers, according to final ratings compiled by Nielsen Media Research.

Another 3.1 million people watched the event broadcast from the Fox Theatre in downtown Detroit on Wednesday night via the CNN Digital livestream, according to the network.

The second of two debates was watched by 7.4 million fewer people than the second of two Democratic debates broadcast last month by NBC, MSNBC and Telemundo. That event in Miami attracted 18.1 million viewers.

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The first night of debates Tuesday drew 8.7 million viewers to CNN's broadcast, with another 2.8 million watching on the channel's digital stream, according to Nielsen Media Research figures.

Wednesday night's event from the Fox Theatre in the Motor City featured Democratic front-runner Vice President Joe Biden Joe BidenPelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Hillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Fox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio MORE in an anticipated rematch with Sen. Kamala Harris Kamala HarrisHundreds of lawyers from nation's oldest African American sorority join effort to fight voter suppression Biden picks up endorsement from progressive climate group 350 Action 3 reasons why Biden is misreading the politics of court packing MORE (D-Calif.), though both candidates were left on the defensive for most of the debate.

Biden was hammered repeatedly from many of the other nine candidates on stage, particularly Sen. Cory Booker Cory Anthony Booker3 reasons why Biden is misreading the politics of court packing Bipartisan praise pours in after Ginsburg's death DHS opens probe into allegations at Georgia ICE facility MORE (D-N.J.) and Harris, while several candidates went after Harris on criminal justice issues based on her time serving as California's attorney general.

Biden has maintained a commanding lead in the RealClearPolitics index of polls with 32.2 percent support, though new surveys conducted after the back-to-back debate nights in Detroit have yet to be released.

During the last election cycle, CNN delivered 15.5 million viewers for its broadcast of the first Democratic debate of the primary season featuring Hillary Clinton Hillary Diane Rodham ClintonFox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio Trump, Biden court Black business owners in final election sprint The power of incumbency: How Trump is using the Oval Office to win reelection MORE, Sen. Bernie Sanders Bernie SandersThe Hill's Campaign Report: Trump faces backlash after not committing to peaceful transition of power Bernie Sanders: 'This is an election between Donald Trump and democracy' The Hill's 12:30 Report: Trump stokes fears over November election outcome MORE (I-Vt.) and former Maryland Gov. Martin O'Malley (D) in October 2015.

The most-watched primary debate in history occurred in August 2015, when more than 24 million people tuned in to Fox News for what was Donald Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE's first debate as a candidate in Cleveland.