Rather, Sanders’s biggest problem is that he’s down 15 to 20 points nationally, a result reflected not only in the national polls but also in the results from states such as Michigan. That means Sanders tends to lose more ground every time a new set of states votes.

That’s especially likely to be a problem for him over the next two weeks, with Florida, Ohio, Illinois and Arizona set to vote on March 17, and Georgia on the schedule for March 24. Even under the best of circumstances, these would not be a great set of states for Sanders. He’s almost certain to lose badly in Florida and Georgia, as he has elsewhere in the South. Ohio and Illinois look like longshots for Sanders, too, given the results in Michigan. Arizona might theoretically be a good state for Sanders, but he’s well behind in the only recent poll there.

And by the time these states have finished voting, the delegate math will be a major problem for Sanders, and even a massive late surge would probably not be enough to help him win the nomination.

Put another way, Sanders needs something like a 20-point surge within the next week just to remain competitive for the nomination, and even then it would still be an uphill battle for him.