The recent debate over the partisan composition of cable news network audiences has focused on data from the Pew Research Center for the People & the Press. As we reported in our 2008 biennial news media consumption survey, there are stark differences in the partisan composition of the Fox News Channel, CNN and MSNBC audiences. And each cable network’s audience profile differs from the partisan balance of the public at large by approximately the same amount.

Among regular Fox News Channel viewers, 39% identified as Republican, 33% as Democrats and 22% as independents. Among regular CNN viewers, 51% identified as Democrats, 23% were independents and just 18% were Republicans. In short, Democrats comprise a larger share of the Fox News audience than Republicans do of CNN’s audience.

However, it should be noted that there are more Democrats than independents or Republicans in the general public. In the 2008 news consumption survey on which this analysis is based, 36% identified as Democrats, 29% as independents and 25% as Republicans.

In terms of partisan affiliation, the audiences for both news networks differed substantially from the public. The Fox News audience was 14 points more Republican than the general public (39% vs. 25% of the public) and three points less Democratic. The regular CNN audience was 15 points more Democratic and seven points less Republican than the general public.

CNN’s audience was not the only TV news audience that was more Democratic than the national average — the same was true of regular viewers of network evening news programs (45% Democratic, 22% Republican) and MSNBC’s regular viewers (45% Democratic, 18% Republican). Both audiences were nine points more Democratic than the general public in that poll.

When independents who lean toward a political party are combined with partisans, a similar pattern is evident. The news consumption survey found that while 49% of the Fox News audience was made up of Republicans and Republican-leaning independents, 39% were Democrats and Democratic-leaning independents. By contrast, fully 64% of regular CNN viewers were Democrats or Democratic leaners, compared with just 23% who were Republicans or Republican leaners.

The regular audiences for Fox News and CNN were equidistant from the general public in terms of leaned partisan affiliation. Half of the public (50%) either identified as a Democrat or leaned Democratic; just a third (33%) identified or leaned Republican. With leaners included, the Fox News audience was 16 points more Republican and 11 points less Democratic than the public; the CNN audience was 14 points more Democratic and 10 points less Republican than the public.

Republicans Migrate to Fox

To some extent, these patterns reflect the migration of Republicans toward the Fox News Channel and away from other TV news sources. Between 1998 and 2008, the share of Republicans saying they regularly watch Fox News rose 22 points, from 14% to 36%. Meanwhile, the share who regularly watch network evening news fell 15 points and the share who regularly watch CNN declined by eight points.

There also has been movement in the regular viewing habits of Democrats. The share of Democrats who regularly watch CNN increased from 25% to 33% between 1998 and 2008, and the share of Democrats who regularly watch MSNBC increased from 10% to 18%. Notably, the share of Democrats who say they regularly watch the Fox News Channel has remained largely unchanged over the past decade (19% in 1998, 21% in 2008).

From 1998 through 2002 there was little difference in the share of Democrats and Republicans using these sources regularly. But in 2004, Republicans moved sharply away from CNN and toward the Fox News Channel. In the 2008 survey, 33% of Democrats regularly watched CNN compared with 17% of Republicans, while 36% of Republicans and 21% of Democrats regularly watched Fox News.

Main Source of News

In addition to the biennial news consumption study described above, the Pew Research Center has a different measure of news usage, asking people where they get most of their news about national and international issues. Because people are asked to pick one or two main sources from a list of news outlets rather than asked about all of the news outlets they might watch regularly, this measure tends to report a somewhat smaller core audience for each source.

Pew Research updated the “main source” measure in the July 2009 news attitudes survey. Among those saying Fox News was their main source of news, 38% were Republican and just 18% were Democrats. Among those saying CNN was their main source of news, 46% were Democrats and just 13% Republicans. Once again, both differed from the balance of partisanship in the general public — the Fox News Channel’s audience was 16 points more Republican than the general public (38% vs. 22%), while CNN’s audience was 12 points more Democratic than the public (46% vs. 34%).

When independents who leaned toward a political party were combined with partisans, the Fox News audience was somewhat further than CNN’s from the national average. Overall, 63% of those who cited Fox News as their main source of news either identified as Republican or leaned to the GOP, which was 27 points more than in the general public (36% in the July news attitudes survey). An identical share of CNN’s audience (63%) identified as Democrats or leaned Democratic, which was 14 points more than the general public (49% in that survey).