2014 exit polls on this:
The 18-29 age group is still the most Democratic age group. They voted for Democrats 54% to 43%. However, this margin is 2 points less than it was in 2010.
More than half of this age group should be under 25, which has been proposed to be more open to Republicans. A two point shift isn't negligible, but it also isn't groundbreaking. These new millennials (at least so far) are significantly more Democratic than the general electorate.
Democrats increased their performance among the 30-44 age group by 6% (winning them 50% to 48%). This is likely due to millennials aging into the group.
Interestingly, Democrats did 6 points better with the 65+ age group compared to 2010. There was probably nowhere for them to go but up after 2010.
http://www.nytimes.com/interactive/2014/11/04/us/politics/2014-exit-polls.html?_r=0#us/2014
The problem with the GOP isn't that it's not seen as "up to the times enough" with young voters. It seems younger voters at least empathize with some ideals of get-out-of-my-bedroom AND get-out-of-my-wallet philosophies ... It's with demographics. Republicans won White young voters; they got killed with minority young voters.
