The Super Delegate system was created after the 1980 election to allow the party establishment to prevent the party from ever going down the road to oblivion as it did with the nomination of George McGovern (1972), which from the day he was nominated was assured to lead to an overwhelming defeat at the polls. (It was a delayed reaction to the defeat in 1972 and driven by Carter's defeat in 1980 as well.) Thus the point was for the Super Delegates to serve henceforth as a safety valve or emergency brake, not for them to put their finger on the scale from the outset in a manner that would favor one candidate over another. Thus the fact that most of the Super Delegates signed on to support Hillary even before Sanders had entered the race was anti-democratic and contrary to the intentions of those who developed this system. So the idea of Bernie's trying to "flip" Hillary's delegates, as distinct from "appealing" to the Super Delegates, is not as anti-democratic as the Super Delegates having signed on as her supporters in the first place. And it should be added that most of the mainstream news media has not even bothered to separate out the Super Delegates from the pledged delegates when reporting Hillary's delegate lead, which had the effect of permitting Hillary's Super Delegate support to weigh in her favor in a highly anti-democratic manner throughout the entire primary contest.
So my main point is that the system of Super Delegates was created as an anti-democratic check on the democratic primary system and with the express intention that the party leaders would look at the national head-to-head polls and that they would exercise their best judgment as to which of the candidates was most likely to secure a victory for the Democrats in November. So while I will readily admit that the Sanders campaign has not been consistent in their statements about the role that has been played, and that should be played, by the Super Delegates, their present position is not inconsistent with the very raison d'etre of the Super Delegate system. And from the latter perspective, the fact that Hillary has received more votes in the aggregate should count as one, but only as one, consideration in the Super Delegates' prudential calculation of where the best interest of the party lies.
Sanders' late surge in the primaries, and the fact that much public opinion polling (which provide objective and scientific snapshots of the electorate's preferences) indicates that he would likely outperform Hillary in a putative head to head match-up with Trump are indeed just the things which the Super Delegates should be looking at when they decide which candidate to favor.
But having signed on in support of Hillary before Sanders entered the race and having prided themselves on their obstinate refusal to reconsider this support even as the polls have indicated that Hillary is a deeply flawed, and perhaps even fatally flawed, candidate, the Super Delegates have undermined the very rationale for their creation in the first place, and this argues for the need to constrain them explicitly through revisions in the party rules that would prevent them from acting in this manner in the future.
As for the A.P.'s signaling that Hillary is the presumptive nominee, my complaint is not so much about their calling the race as it is about the manner in which the Super Delegates have usurped their proper role, which is what gives the A.P.'s call whatever putative validity is possesses.
And as for Obama's possibly coming out tomorrow to back Hillary, irrespective of the outcome in today's primaries: this is only problematic if one believes that the Super Delegates should objectively and impartially assess the pros and cons of going with Hillary or Bernie, before making their final and irreversible decision. Obama is after all the most super of all the super delegates and his public endorsement of Hillary will surely work to keep the rest of the super delegates in line. Ditto Nancy Pelosi's endorsement today. But in proceeding thus, these personifications of the Democratic Establishment are acting in a manner that weighs heavily against the Super Delegates performing their appropriate, and appropriately circumscribed, task.
Addendum re How to Change the Rules re Super Delegates:
In response to the
question of how the Democratic Party might reform the rules that govern the
role that is played by the Super Delegates, I would propose the following change
in the Democratic Party rules: The new rule should be that no Super Delegate
should be permitted to endorse any presidential candidate until after the end
of the primaries. After all, the Super Delegates were created to help make sure
that the party does not err by nominating a candidate who is unlikely to be
able to win the general election. The Super Delegates were created as an
anti-democratic emergency brake, who in most circumstances should and will
FOLLOW the will of the party rank and file not LEAD it. But this clearly
implies that they should not endorse early on in a manner that tilts the
playing field on behalf of one candidate or another, before the Democratic
electorate has had its say. Also, by endorsing earlier rather than later, the Super
Delegates undermine their very ability to serve as an impartial
late-in-the-game emergency brake. Thus we should all petition the Democratic
Party's Rules Committee to make this change which would be applied starting
with the 2020 presidential nominating contest.