For Conservatives It Is all About Fox News
The number of places conservatives in this country get their news is remarkably narrow and consists mainly of Fox News, and to a small degree talk radio. From Pew:
In addition, while Liberals and Mixed tend to trust all the other major news networks (CNN, ABC News, NBC News and CBS News) except Fox News, basically the only news network source Conservatives trust is Fox News.
Among conservatives in this country reality is effectively what Fox News says it is, and since the conservatives are a deciding force in Republicans primaries, Fox News also defines reality for the Republican party.
That is an incredible amount of power for one network to have in an age when it has never been easier to access multiple news sources.