Every other story written by journalists across the country gives a spreadsheet of reasons why Hillary Clinton should step out of the Democrats’ campaign.

Yet in the public’s eye, there she stands as though she has not a care in the world.

One reason may be that the party’s super-delegates who remain uncommitted have an unspoken burden of proof to determine whether this race goes on or not. So far, they have not exercised their superpowers.

Since no one has called a swift press conference en masse behind Barack Obama, could it be that neither candidate has fulfilled that burden of proof?

Clinton emphasized recently that super-delegates have a responsibility to exercise their judgment not only as to who would be the best president but also as to who would be the strongest nominee.

“I believe that the super-delegates should do the same as any other delegate or voter, which is to determine who they believe will be the best president,” she said.

“Hillary Clinton is on a path to victory that isn't outside the realm of possibility, so it makes sense for her to stay in,” says political science professor Matt Lebo at New York's Stony Brook University.

A Clinton win in Pennsylvania will give her momentum to win Indiana, Kentucky and West Virginia. If that happens, her net popular votes would match – and possibly pass –Obama’s.

At that point, Lebo says, Clinton has a chance to convince 55 percent to 60 percent of the super-delegates that she should be the nominee. “That scenario is possible, though unlikely," he points out. “Convincing pledged delegates to ignore their pledges on the first ballot at the convention is very unlikely, and a second ballot looks equally unlikely at this point.”

Part of the equation that keeps Clinton confidently in this race is delegate math. Contrary to popular belief, not much separates a pledged delegate from a super-delegate; each can exercise free will and change his or her mind. Continued...