Mass communication research, Rogers and Dearing argue, has focused a great deal on ""public agenda setting"" (e.g. McCombs and Shaw, 1972) and ""media agenda setting"", but has largely ignored ""policy agenda setting"", which is studied primarily by political scientists. As such, the authors suggest mass communication scholars pay more attention to how the media and public agendas might influence elite policy maker's agendas (i.e. scholars should ask where the President or members of the U.S. Congress get their news from and how this affects their policies). Writing in 2006, Walgrave and Van Aelst took up Rogers and Dearing's suggestions, creating a preliminary theory of political agenda setting, which examines factors that might influence elite policy makers' agendas.