The study from Vanderbilt researchers Joshua Clinton and Ted Enamorado says existing members of Congress became more conservative after the advent of Fox News in 1995. Districts where the new channel started broadcasting saw their Representatives move to the right compared to their political stance before Fox News. Fox News did not have any impact on the ideological standing of newly elected members of Congress.
The study did not find that the media had any affect on the outcome of elections.
We use a unique opportunity to determine whether position taking behavior in Congress and the likelihood of incumbents being challenged is affected by the national news media. Using the fact that the Fox News Channel was launched in October 1996 and it gradually spread across congressional districts in the United States in a manner unrelated to the ideology of the district and the incumbent representative, we show that there is a modest effect on elected officials' positions - representatives from districts where Fox News begins broadcasting become slightly more conservative relative to similar representatives in otherwise similar districts where Fox News is not present. Given the distinctive ideological content of Fox News, the effect is predictably largest among the more liberal members. However, we found no evidence that Fox News affected which representatives were re-elected or replaced. Overall, our results suggest that the national media may have a slight effect on the prospects for policy change by affecting representatives' expectations and causing them to slightly adjust the positions that they take.