This doesn't mean that they are doing what they can to help Democrats win the election. In fact, what it means is that they are playing up the big story of this election time: Holy Jesus, the Democrats might actually win something! This is exemplified in this quote:
What, exactly, should they be reporting on right now as far as the election goes?
Except that the reporters don't have much power in the media industry. Just because the reporters are liberal/democrats doesn't mean crap honestly. Its why most of the studies that have come out show that news coverage on a whole is pretty centrist, while the editorial pages are far less centrist.
The people that have the power are the owners of the media outlets. They're the ones that set the tone for the entire organization, and they do so for profit interests, which leads back to all of the things I posted above.
The key is that the reporters don't have the power, the owners do. The owners are greedy bastards who want money, and make sure that their news outlets do everything possible to get money.
Most of the long-term scholarly research shows that reporting by the major media firms is, on average, much more centrist then either party wants to believe. The studies have also shown that people will feel that media coverage is biased against their own side. You see that in this very thread, with you feeling that they do everything they can to help the Dems win, while the liberals in this thread feel that its very biased toward Republicans.