Bernie Sanders lost any chance at the Democratic nomination a long time ago. He didn't lose because the system was rigged against him, he didn't lose because of a conspiracy within the Democratic Party. He lost it fair and square.

He lost it in the voting booth, where he trails Hillary Clinton by more than 3 million ballots. He lost it in the delegate count, in which Clinton leads 2,291 to 1,528. If you want to exclude superdelegates from the count, fine. Sanders also lost it in the earned delegate count, where he trails Clinton by 279, with no chance of making up that margin in the remaining few primaries.

In short, he lost.

Nonetheless, despite the clear verdict of primary voters and caucus attendees, Sanders and at least some of his followers appear to believe that the nomination ought to be given to them anyway. Judging from their rhetoric, they believe that they deserve it because they believe that they are very very right and everybody who disagrees with them is very very wrong and also corrupt and stupid.

I don't like that kind of arrogant self-righteousness coming from the right, and I don't like it any better coming from the left. I also don't like the outburst of personal threats, misogyny, abusive language and attempted intimidation that came from Sanders supporters in wake of last weekend's Democratic state caucus in Nevada.

Back in February, Clinton won the actual Nevada caucus by more than five percentage points. Based on that margin, it was estimated at the time that she had won 20 delegates and Sanders 15. But Saturday, at the state convention called to finalize that delegate count, the Sanders campaign attempted to overturn the voters' decision. After considerable maneuverings, heated rules fights and protests, they lost that battle too. The final delegate allocation was 20 for Clinton and 15 for Sanders, an outcome that fairly reflected the choice of caucus attendees.

Sanders supporters found that not just unacceptable, but a monstrous outrage and evidence of the duplicity that they claim is stealing the prize they deserve. Afterward, the state party chair was attacked viciously on Twitter, in emails and phone calls. Her employer was threatened, as were her family and grandchildren. Physical violence was threatened repeatedly, and in explicit terms. "I think people like you should be hung in a public execution," one caller said in one of the milder reactions.

Such behavior has no place in politics and ought to be condemned strongly. But given the chance to do so, Sanders has declined.

In a statement released this week, he noted almost in passing that "Our campaign of course believes in non-violent change and it goes without saying that I condemn any and all forms of violence, including the personal harassment of individuals." But the remainder of his lengthy statement -- basically a rehash of his campaign's grievances -- reads as an attempt to justify what had happened and explain why it was necessary.

There can be no such justification, and Sanders is treading dangerous ground here. A leader is responsible for what his followers do. That's the essence of leadership. And a half-hearted condemnation in passing can easily be read by followers as an implicit form of permission.

To this point, Sanders has earned a considerable amount of respect and has succeeded in shifting the internal Democratic debate in a direction that it badly needed to go. He has accomplished a lot, but he is placing all that and more at risk now. He says that he still has a message that he wants to communicate, and that's fine. But if you are more interested in "sending a message" than you are in the real-world consequences, if you indulge yourself in conspiracy theories to explain away your own failure, then those who do care about the consequences have every right and indeed the obligation to oppose you. Because the consequences are real.

The consequences of Ralph Nader's destructive vanity campaign in 2000 -- the election of President George W. Bush, the subsequent invasion of Iraq and perhaps the economic meltdown of 2008 -- were very real. The consequences of a Donald Trump presidency would likely be far more traumatic.

As a leader, Sanders has the obligation to himself, his cause, his followers and his country to rethink where this thing is headed, and to take a wiser course.