Opinion - What comes first: the chicken of partisanship or the egg of media leaning?

In a recent discussion with The Professor, we touched on the topic of the immigration issues in the United States. My interlocutor supported the notion of a giant wall, justifying his views with claims that "it worked for Israel". Having read about it and having watched a Daily Show the previous night (which discussed the problem at length), I countered with Jon's (reasonable to my ears) arguments that

1. the mostly Hispanic workforce does the Fight Club jobs that nobody wants, and
   
2. that they have no incentive to commit sex crime (or any other crime for that matter) as they would be immediately deported.

I was promptly dismissed with "you are just parroting the liberal media". This was, of course, a typical paternal provocation, but did also have more than a grain of truth to it. I had to think.

The recent Rumsfeld row also triggered some musing, when I accidentally stumbled on a Fox news poll entitled "What do YOU think of the job Rumsfeld has done as Defense Secretary? Is it time for him to step down?" and read the comments (you can imagine what they are). This brought back memories of Cheney and his media demands.

In the pick'n'mix post-Internet media world, it is possible to hear only what you wish to hear. Now I wonder: does the media that we enjoy lead us to the views that we harbour, or do our views guide us to the media that we enjoy? For me personally, I hope that it is mostly reason 2 but I just don't know anymore.