Thursday's debate between Vice President Joe Biden and Wisconsin Rep. Paul Ryan attracted 51.4 million viewers, becoming the second-most-watched event featuring vice presidential contenders since 1984, when George H.W. Bush sparred with Geraldine Ferarro.
However, the showdown four years ago between Biden and former Alaska Gov. Sarah Palin easily maintained its record as most-watched, according to ratings firm Nielsen. Nearly 70 million people watched the 2008 debate, the first and only between those vice presidential hopefuls.
The 1984 contest between Bush and Ferarro generated an audience of 56.7 million, Nielsen said.
Last week, 67.2 million people watched the first presidential debate between President Obama and Republican Mitt Romney. Analysts criticized Obama for a weak performance, and Romney has since seen a bump in the polls among likely voters. The next debate between Romney and Obama is scheduled for Tuesday at Hofstra University in New York.
Once again, the over-55 crowd -- the group with the highest rate of voting in elections -- came out in force to watch Thursday's debate, held at Centre College in Kentucky and moderated by ABC News correspondent Martha Raddatz.
Nielsen found that more than 26.7 million people ages 55 and older watched Ryan take on Biden. Nearly 15 million people ages 35 to 54 watched, as did 7.15 million viewers ages 18 to 34, Nielsen said.
Ten television networks -- ABC, CBS, Fox Broadcasting, NBC, PBS, CNBC, CNN, Current TV, Fox News Channel and MSNBC -- provided live coverage of Thursday's debate. Two Spanish-language TV networks, Univision and Telemundo, provided their coverage on a tape-delay basis.
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