One of the biggest factors the Democrats had for mobilizing the youth vote was Comedy Central. The Daily Show and Colbert Report were ostensibly comedy news shows but the news they showed was typically one-sided.
I stopped watching the Daily Show during the 1990s when I noticed that Jon Stewart's opening monolog always contained points from the White House message of the day.
Stewart's main bit was to take the news and put it into "perspective." If it was bad news for the left then he would contrast it with something worse the right did. If it was good news for the right then he'd manage to put a negative spin on it. If it was good news for the left or bad news for the right then he'd dance a little jig.
Stewart likes to have things two ways. He insists that he can't be held to standards of fairness or accuracy because he's a comedian who "makes things up" but he also likes to lecture the news media on what the are doing wrong. He gets away with this because he says what hi audience wants to hear.
He has a reputation as a soft interviewer. This is partially deserved. He is good at prompting people to get their message out - as long as he agrees with that message. If he doesn't then the person being interviewed can count on it being cut to make him look bad.
The Colbert Report was slightly different and evolved over time. The original premise was that Stephen Colbert was playing a conservative commentator but was actually a liberal. In fact, during the early years, the joke was often on the left. Colbert went for the joke and gained the reputation as a hard interviewer. He typically began interviews with liberals by asking, "George Bush, great president or greatest president?" It got to the point where Democrats refused to come on his show. During a writer's strike Colbert was (officially) working without writers. During that period he was at his most fair and unbiased.
When the strike ended, the show took a sharp turn to the left. This paid off for Colbert. Not only did the Democrats start coming back on his show, he started getting invited to the White House.
Colbert's attacks were always unfair and sometimes verged into outright mean. During the 2012 campaign he devoted two separate segments on telling us how weird it was that Romney's wife practiced dressage (an intricate form of horseback riding sometimes called horse ballet) and how silly it was that Romney had an Olympic entry in dressage. Keep in mind that this is an Olympic sport that takes years of practice for the horse and rider. Colbert distilled this down to wearing a child's cowboy hat and going "giddy up" while slapping his rear.
A number of polls showed that a large chunk of the youth vote got their "news" from the Daily Show and Colbert Report. With these gone, will the Democrats have a voice left to comfort the youth vote in 2016?
