Joe Biden is the elephant in the Bernie Sanders echo chamber. He's trailing Sanders by a mere 6 points in poll aggregates, and he polls better against Bush and Trump than Sanders.

Now, granted, he's better-known nationwide, but for a candidate who hasn't even announced he's running, he's doing surprisingly well. If he does announce he's running, I wonder how many people, frustrated by Clinton, might switch their vote from Sanders to Biden just because Biden is a safer bet on paper to defeat Clinton and win the general election.

One thing's for sure, though. If Biden runs, the most heated race in the Democratic primaries will be Sanders vs. Biden, not Sanders vs. Clinton.