Bernie Sanders’ case for why he will be the Democratic nominee goes something like this: He will end the campaign close to even with Hillary Clinton in pledged delegates, and then make a persuasive argument to the party’s superdelegates, flipping enough of them to his side to get him over the threshold.

But a POLITICO analysis of the Democratic delegate math reveals that even under a best-case scenario, in which Sanders sweeps the nine remaining contests and picks up every undecided superdelegate still on the board, the Vermont senator would still need to persuade nearly 200 Hillary Clinton superdelegates to bolt from her camp — a feat of political engineering that would make the moon landing look like a walk in the park.


Sanders himself has said on multiple occasions that the more contests he wins, the more pro-Clinton superdelegates would rethink their allegiance. In a late March interview on CNN, after winning Democratic contests in Alaska, Hawaii and Washington state, Sanders said "a lot of these superdelegates may rethink their positions with Secretary Clinton.”

But so far, her superdelegates have shown no indication of going wobbly: Not a single one has changed sides this year, despite significant pressure to do so in the states Sanders has won.

In 2008, less than three dozen Democratic superdelegates ultimately switched sides.

“There’s really no history of superdelegates changing their candidate commitment,” said a veteran delegate allocation expert who requested anonymity to speak freely. “Maybe a handful of switchers in a whole presidential cycle. We certainly haven’t seen any this year and it’s unreasonable to expect it now.”

A different consultant involved in delegate operations for multiple presidential campaigns explained the heavy pressures weighing against flipping.

"It's a) a big personal engagement, usually involving the candidate directly and b) you've got to get somebody to say, ‘You know what? I know I committed here and I’m going to burn a bridge that I’m never going to repair.’ Because when you’re a superdelegate and you move, it’s not something that people easily forgive,” the operative said.

According to The Associated Press, Clinton had 1,769 pledged delegates and 543 superdelegates through Wednesday, for a total of 2,312 delegates. That puts her 71 short of the 2,383 she needs to claim the nomination.

Sanders, meanwhile, had 1,501 pledged delegates and 44 superdelegates for a total of 1,545 — 838 delegates short of the threshold for nomination.

Even under a highly optimistic scenario in which Sanders claims two-thirds of the 781 pledged delegates still available in the remaining nine contests — and picks up every one of the 133 undclared superdelegates — he’d still need to persuade at least 185 Clinton superdelegates to jump ship.

The Sanders campaign argues that it can make up substantial ground among superdelegates who hail from the 20 states he won — at present, Sanders has the support of just 26 superdelegates from those states, compared to 108 for Clinton. Between persuading superdelegates to follow their state’s popular vote and pointing to the fact that Sanders has a considerable lead over presumptive GOP nominee Donald Trump in most head-to-head polling match-ups, the campaign believes it has a persuasive case to make.

"We believe that we can make substantial progress between now and the end of voting. Right now the percentage of pledged delegates is 54-46, that we would get it to 50-50," Sanders chief strategist Tad Devine said Tuesday. "If we come a little bit short, I still think we’re going to be in a very strong position to argue that — if you look at the progress that Bernie made, if you look at the standing that he has, particularly versus Trump in the polls, if you look at where we started and where we finished. It’s a very, very strong argument that he would be the best choice to be the nominee. I think we’ve all resolved, ‘why don't we let the voters have their say first’ and our goal is to tie this thing up.”

While Sanders is correct when he says that many of the Clinton superdelegates lined up with her before voting started — and before the strength of his campaign was apparent — the fact that not one superdelegate has flipped over the course of the primary season suggests that many of them still view Clinton as the strongest possible Democratic nominee.

“I can’t see it happening,” said Marianne Stevens, a Maine superdelegate in 2008 who backed Obama after he racked up 10 wins in a row.

“I think most of the people that are the superdelegates, and this is even taking out the elected officials, the senators, the congressmen. If you just look at the DNC members, ... they want to win in November. So they're going to look at the stronger candidate, and I cannot see that any of them would look at Bernie Sanders as a stronger candidate against a Trump.”