Behind the War Between White House and Fox - NYTimes.com: "...officials at the White House had decided that if anything, it was time to take the relationship to an even more confrontational level. The spur: Executives at other news organizations, including The New York Times, had publicly said that their newsrooms had not been fast enough in following stories that Fox News, to the administration’s chagrin, had been heavily covering through the summer and early fall..."
The New York Times says that the White House decided to go after Fox News because Fox was doing too good a job of covering the White House. Fox broke stories that the other major media outlets initially ignored, and then when the stories proved to be true and big, were forced to cover. So, when Fox started leading the way for the rest of the herd, the White House decided to try to demonize and isolate Fox, in the hope that stories broken there will stay there and will not be picked up by the New York Times, et al.
How do you like that, Obama lovers? Is this the new tone you were looking for?