Research has shown that messages of intra-party harmony tend to be ignored by the news media, while internal disputes, especially within the governing party, generally receive prominent coverage. We examine how messages of party conflict and cooperation affect public opinion regarding national security, as well as whether and how the reputations of media outlets matter. We develop a typology of partisan messages in the news, determining their likely effects based on the characteristics of the speaker, listener, news outlet, and message content. We hypothesize that criticism of a Republican president by his fellow partisan elites should be exceptionally damaging (especially on a conservative media outlet), while opposition party praise of the president should be the most helpful (especially on a liberal outlet). We test our hypotheses through an experiment and a national survey on attitudes regarding the Iraq War. The results show that credible communication (i.e., "costly" rhetoric harmful to a party) is more influential than "cheap talk" in moving public opinion. Ironically, news media outlets perceived as ideologically hostile can actually enhance the credibility of certain messages relative to "friendly" news sources.
Baum, Matthew A. "Shot by the Messenger: Partisan Cues and Public Opinion Regarding National Security and War." Political Behavior 31.2 (June 2009): 157-186.