As this video incisively illustrates, the media hates Ron Paul, and they hate him more the more popular he gets with the electorate. As John Stewart notes in the clip, Ron Paul is the original Tea Partier, and given the love shown by the media to the Tea Party it is odd that the intellectual founder of this organization does not get more attention. However, the reason for this disconnect is actually quite clear when we adopt and analyze the situation using the Propaganda Model of the Media developed by Chomsky and Herman in their seminal work, Manufacturing Consent.
In this work, Chomsky and Herman identify five filters that they argue shape media coverage in the US. One of these filters is Flak, which is criticism aimed at the media by popular elites for statements or comments that question the established media narratives. Ron Paul is popular because he raises powerful criticisms about US foreign and domestic policy; criticisms that are completely ignored by the major political leaders in this country and by their opponents. There was literally zero difference between the foreign policies of Barack Obama and Mitt Romney. Since Ron Paul's criticisms fall outside this range of establishment opinion that is tolerated by the Mainstream Media, they must be attacked, and the bearer of these criticisms must be marginalized.
For more on this topic I recommend this excellent article by Glenn Greenwald.