It's the math, stupid! This from Jonathan Alter over at Newsweek :

Let's say the Democratic National Committee schedules do-overs in Florida and (heavily African-American) Michigan. Hillary wins big yet again. But the chances of her netting 56 delegates out of those two states would require two more huge margins. (Unfortunately the Slate calculator isn't helping me here.)

So no matter how you cut it, Obama will almost certainly end the primaries with a pledged-delegate lead, courtesy of all those landslides in February. Hillary would then have to convince the uncommitted superdelegates to reverse the will of the people. Even coming off a big Hillary winning streak, few if any superdelegates will be inclined to do so. For politicians to upend what the voters have decided might be a tad, well, suicidal.

For all of those who have been trashing me for saying this thing is over, please feel free to do your own math. Give Hillary 75 percent in Kentucky and Indiana. Give her a blowout in Oregon. You will still have a hard time getting her through the process with a pledged-delegate lead.

Alter used Slate's Delegate Calculator to calculate the total.