Some 63.6 million people watched the second debate between presidential candidates Donald Trump and Hillary Clinton on Sunday night, Reuters reports.
The number is a sharp fall from the first, record-breaking debate which was watched by 80 million people.
The 63.6 million figure was released by Nielsen for 10 broadcast and cable channels. Final figures will be released by Nielsen later, and will not include millions more who watched the debate online, through social media or in bars and restaurants.
Second presidential debates tend to attract smaller TV audiences, noted Reuters, but attention on Sunday's debate was high after the emergence of the 2005 Trump video in which he made lewd comments about women.
However, the second debate took place in the same time slot as NBC's popular "Sunday Night Football," which was watched by about 15 million Americans, Nielsen data showed. NBC did not carry the debate.
A final TV audience of 64 million to 65 million would place the debate out of the nation's top 10 most-watched presidential encounters, and below that for President Barack Obama's first and second 2012 debates with Republican challenger Mitt Romney, according to Reuters.
Last week's vice presidential debate between Republican Mike Pence and Democrat Tim Kaine drew 37 million Americans - the lowest audience for a VP debate since 2000.