In the wake of his convincing 15-point defeat in the New York Democratic primary, Sen. Bernie Sanders trails badly in terms of pledged convention delegates. His opponent, Hillary Clinton, has a lead of 2.7 million votes in the popular vote as well. If the polls prove accurate, Clinton will also do very well in the five primaries scheduled for next Tuesday, extending her lead in delegates and popular support and making it all but impossible for Sanders to claim a majority.

Yes, a lot of that lead and a lot of those delegates have come as a result of Clinton victories here in the South, as Sanders has pointed out often. But we count too.

In an interview on MSNBC this week, Sanders campaign manager Jeff Weaver suggested that Clinton's overall performance shouldn't dictate the outcome of the race. Even if Clinton ends the primary season ahead of Sanders both in terms of earned delegates and the popular vote, Weaver said, the Sanders campaign will attempt to convince the party's 719 unpledged superdelegates to overturn that outcome and make Sanders the nominee.

That is a very bad idea.

In practical terms, it is a bad idea because it is doomed to failure. Those 719 superdelegates are the Democratic establishment, the party leaders and elected officeholders, and the notion that they are going to reject Clinton in favor of Sanders, and by doing so ignore the opinion of Democratic voters as it has been expressed in the voting booth, is ludicrous.

It is also a bad idea because it would contradict much of what Sanders and his supporters have claimed to champion in their surprisingly successful "up from the grassroots" campaign. From the very beginning of the race, the Sanders campaign has presented itself as a popular uprising against the establishment. It has insisted that the nomination ought to be decided by actual Democratic primary voters, not by party bosses and unelected superdelegates representing the establishment.  As recently as a month ago, Sanders was arguing that superdelegates from states that he has carried had a moral obligation to listen to their constituents and vote for him at the convention.

"It would be insane, even by the corrupt standards of the Democratic National Committee, if a small group of party elites went against the will of the people to choose the presidential nominee," as one Sanders supporter argued back in February, in the heady days after Sanders won New Hampshire.

If Sanders is now willing to throw that all aside by arguing that the opinion of the grassroots voters ought to be overturned in his favor by party insiders, then he exposes himself and his crusade as frauds. He tells his followers that in the end, when forced to choose between standing by his principles or grasping at power, he too chose to grasp at power. He tells them that despite his stirring rhetoric, this had really been all about him, and not about them.

That would be a terribly disillusioning way to end a campaign that inspired millions.

Sanders has the right -- indeed, he has the obligation to those who have supported him so steadfastly -- to fight for the nomination as long as he has a chance of winning a majority of his party's voters and earned delegates. But by his own standards, that is the only legitimate means of winning, and if that opportunity ends, the rationale for his campaign ends with it.