Combo photo shows former US Vice President Joe Biden (L) and US President Donald Trump attending their respective events on different occasions. Photo:Xinhua

US President Donald Trump's acceptance speech drew fewer viewers than that of Joe Biden, former vice president and 2020 Democratic presidential nominee, according to data released by Nielsen Media Research on Friday.

An estimated 19.9 million Americans watched Trump's speech from the White House South Lawn during the finale of the Republican National Convention (RNC) Thursday night on television, while Biden drew 21.7 million viewers a week ago.

By comparison, 34.1 million tuned in to watch then Republican presidential candidate Trump deliver his keynote speech during the 2016 RNC.

The ratings were based on nine television networks for the fourth night of both the Republican and Democratic conventions. These figures do not include the number of people who watched the presidential nominees' speeches online.

Fox News led all networks in viewership, drawing 9.9 million viewers in total for four nights of the convention, and beating ABC, NBC, CNN and MSNBC combined. ABC came in second, with 2.58 million viewers, followed by NBC with 2.28 million viewers.