With the couple months' news Hillary has been having, it's no surprise Biden is outperforming her. Most people still aren't paying that much attention yet, but it's nearly impossible not to have heard something about Hillary's email, which judging by her word association, isn't good for her. Granted, the GOP is enough of a mess that she still might win anyway.
Republicans have complained for the longest time that the media ignores Biden's gaffes as "just old Joe". If he's had the same scrutiny that Hillary has had, doubt he would be as strong.
http://thehill.com/policy/international/191855-biden-to-japanese-women-do-your-husbands-like-you-working
This alone is pretty devastating and more gaffetastic than many of Jeb's blunders.
That's a fair point, but only politicos are paying attention to Biden right now with any kind of scrutiny. There's no telling Biden's polling would hold up if he actually entered the race, but with as unpopular as pretty much everyone in this poll, it should be no surprise Biden polls better.
