From a research paper "
How Fox News Changed American Media and Political Dynamics
by Bruce Bartlett. The entire paper can be read at http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2604679
Also from the paper which argues that Fox News has been bad for Republicans. "People who watch Fox News, the most popular of the 24-hour cable news networks, are 18-points less likely to know that Egyptians overthrew their government than those who watch no news at all (after controlling for other news sources, partisanship, education and other demographic factors). Fox News watchers are also 6-points less likely to know that Syrians have not yet overthrown their government than those who watch no news.[!]"
He argues that Fox is less a "conservative" network than a "partisan" one.
"Although this arrangement unquestionably aids Republicans in winning elections and votes in Congress, it is not without its downsides. One is that Fox now exercises such powerful control over the GOP that it has become the party’s kingmaker in presidential primaries.56 Indeed, during the 2012 election cycle, a number of aspirants for the Republican nomination had been paid Fox commentators, including Newt Gingrich, Rick Santorum, Sarah Palin and Mike Huckabee.57 And woe to the Republican who runs afoul of Fox’s top brass or ignores their advice, as Mitt Romney did on one occasion in 2012.58 Fox is now so important in GOP primaries that candidates must put aside pressing campaign concerns when summoned to a Fox interview, where any error is magnified within the Republican bubble."
"Fox has now become a problem for the Republican Party because it keeps a far right base mobilized and angry, making it hard for the party to move to the center or increase its appeal, as it must do to remain electorally competitive….One of the reasons Mitt Romney was so unable to pivot back to the center was due to the drumbeat at Fox, which contributed to forcing him to the right during the primary season. Even after the primary season, when Fox became a big supporter for Romney, the rift between official editorial position and the political feelings of Fox viewers and hosts was clear."