The Democratic primaries are still many months away, and far too much is yet to happen that will determine which candidate is actually the most electable. Mr. Biden has a clear advantage in name recognition given that he has served in the White House before. That upper hand will narrow as people get to know the other candidates on the campaign trail. The race could go in so many directions, and a number of Mr. Biden’s competitors could easily become a surprise standout. We’ve seen it happen plenty of times before. Or perhaps Mr. Biden really will prove the strongest option. Time will tell.