The ideological bent of cable news channels like Fox News and MSNBC are often seen as the reason for the increasingly coarse language and attitudes in national politics.
Markus Prior, associate professor of politics and public affairs at Princeton, says it's not cable news per se, but the explosion of more entertaining choices Americans now have when it comes to their media diets...
From The Economist:
In the glory days of network television, in the 1960s and 1970s, he writes: "Even people with little interest in news and politics watched network newscasts because they were glued to the set and there were no real alternatives to news in many markets during the dinner hour." However once viewers had a greater array of choices, those bored by politics gratefully turned to more entertaining channels and shows, he suggests: "The culprit turns out to be not Fox News, but ESPN, HBO, and other early cable channels that lured moderates away from the news and away from the polls."
In essence, the people who were once forced to be informed (everyone) can now turn off the news and disengage from the political process entirely. Most of them being moderates.