What explains the fact that debates this year are garnering almost twice as many viewers as any of the early debates, Democratic or Republican, did four years ago? Cable news executives don’t know for sure, but they have theories. Chief among them is that widespread anxiety about the economy and disapproval of the political system is building viewership…

Other theories involve livelier contenders, showier production values for the debates and an increase in online chatter about them — some of the same traits that make reality TV shows successful…

Debates have been focal points of the Republican campaign to a greater degree than they were in 2007 and 2008. While the candidates are traveling and speaking in early primary states, “a debate is a much better way for them to see all of them at once,” Mr.Clemente said, referring to voters.

Because there are no debates on the Democratic side this season, Democrats may be tuning in to the Republican debates earlier than they did in 2007 to sizeup the competition for Mr. Obama.