Most of the media isn't against Trump because he's republican. They're simply reporting and investigating. Since Trump and his administration are incompetent it can seem like they're all out to get him, I suppose. You could argue certain far left places/people (kos, certain msnbc hosts) are against him by default.
The problem isn't that FOX and breitbart exist. It would be nice if they didn't function as propaganda outlets, but what might be nicer is if conservatives actually got their news from different places. The older people in my area are great examples as I posted before. I'm in their homes frequently and it's extremely common for them to just play FOX news all day. They turn it on when they get up it and it just sits there. They don't ever look at CNN/MSNBC/network news. They (older folks anyways) don't browse different websites to get balanced commentary or news.
Yesterday's FOX programming was a good example of how that can be damaging. Millions of conservative have no clue what's really going on because they trust FOX.
Trump is a dumpster fire of a president. Of course you're going to see a ton of negative stories from both the middle and left leaning news outlets.negative stories about Trump