Everyone has biases, and opinions.
I think this question (put forth by someone else, apparently 4 months ago) has an obvious answer: yes; some of them. I think that the casters themselves are not really bringing their personal opinions to the table (unless you count that lady in the now infamous video, trying to bring sense to the nutbar behind harassing attendees of military funerals); what they are working on is the general opinion of their viewers from what they've recieved via polls.
If the polls say be pro-such-n-such party.. they will. If they say that the majority of the viewers believe something, the news takes on that tone. I would rather it be objective, but, apparently, in Canada, objective has been taken over by the opinion that mud-slinging is a-okay. Whether or not it fuels our collective love of dirty laundry, we'll probably never know -- the polls would dictate that outcome, too.
I sort of prefer "news" as done by Rick Mercer/The Royal Air Farce -- yes, it's biased, but there's a take-no-side/take-no-prisoners attitude to both's approach. Then again, whenever the negative truth is presented in humor, it is typically absorbed and processed.
I think that the people running the news have a strange idea of what we want to see. I myself want to know about more world news, but basic, free channels, only tell people basic details on anything political. There's local events, and, with that, all we really get are brutal accidents/attacks, or sunshine stuff about good deeds. I think that Global, the company that handles the media for people without cable/satellite, gives more coverage to sports than it would ever to to the Korean/Russian situation. As far as I can tell, nothing new is really happening in sports.
The newspapers are mostly using filler for framing ad-space. In my local one, we dedicate at least a page an issue to the water meter referendum. Apparently, with this, they know that the readers' opinions are gold -- or, good for pandering to the readers. I think it's sort of like the polls, only with explanations behind the chosen options.
Anyway: point -- yes, the news is opinionated, but, mostly leaning in a way that the providers think best keep their viewers watching them.