Still think the Democrats have this election locked up—and that between their 242-vote head start in the Electoral College, and Donald Trump’s ongoing identity crisis, the only cloud on the horizon is whether or not the inevitable Republican meltdown is big enough to cost the GOP control of the House as well as the Senate? Well, think again. Just because the presidency looks like Hillary Clinton’s to lose doesn’t mean it can’t be lost. Last weekend the Nevada Democratic Party held its state convention in Las Vegas, but instead of a stately coronation, the proceedings ended in an ugly melee, with state party chair Roberta Lange shutting down debate behind a screen of uniformed police while enraged Sanders backers cursed and threw chairs. Footage like this from Philadelphia could cost the Democrats the election.

The national press stopped paying attention to Nevada on February 21, when the party held precinct-level caucuses—a contest Hillary Clinton narrowly won (how narrowly we’ll never know, since Nevada does not report the raw vote totals), giving her 13 delegates to 10 for Sanders. But that was just the first step in a three-tier process to choose Nevada’s delegates.

Clinton’s lead in the precinct caucuses also meant she got more delegates to the county conventions on April 2—which in turn elected delegates to the state convention. If that sounds confusing, don’t worry—it’s supposed to be. Complicated procedural rules are one way party insiders keep outsiders outside.  What Harry Reid and the state party—who had their thumbs on the scale for Clinton all along—hadn’t expected was to be outmaneuvered at the county convention, where the Sanders forces, who got more of their people to turn out, elected 2,124 delegates to the state convention against just 1,722 for Clinton.  If that margin had held up last weekend—and if Sanders had held on to the two delegates he picked up at the Clark County caucus—the Vermonter might have claimed Nevada as a win.

Instead Sanders supporters say the Nevada party changed the rules—and then changed the procedure for deciding challenges to the rules. Then at the state convention the party excluded 58 Sanders delegates—enough to now give the 1,695 Clinton delegates who turned up a majority over the 1,662 Sanders delegates who were ultimately accredited.  Party officials said the excluded delegates either were not registered as Democrats or did not provide sufficient personal information to verify their registration.

The substantive disputes may ultimately be settled in court—a long time after the November election. What’s worth pointing out right now, though, is that this whole debacle was over—at most—three delegates in July! If the Sanders supporters had carried the day, they would have gone to Philadelphia with 18 delegates to Clinton’s 17; instead they remain behind Clinton 20 to 15.

Hillary Clinton’s failure to clinch the nomination has understandably left many of her supporters bad-tempered about Sanders’s refusal to concede. Last week former Kerry spokesman David Wade called Sanders a “zombie candidate,” while his Politico stablemate Bill Scher unleashed the ultimate putdown, comparing Sanders to… Ralph Nader. In that kind of media climate there is no point in being subtle—so I won’t. If Hillary Clinton doesn’t stop being such a sore winner, she may well end up a sore loser. A candidate with 524 superdelegates in her pocket—and a lead of 291 in pledged delegates—can afford to be gracious. Even if it means that lead shrinking by two or three delegates.

Because while its true that, no matter how well he does in Oregon and California, Bernie Sanders is unlikely to win the nomination, it is equally true that unless Clinton is able to convince a large proportion of Sanders supporters to vote for her, she’s unlikely to win in November.

So while she, and her supporters, may well resent still having to pay attention to Bernie Sanders, they’d better learn to swallow their disappointment just as, eventually, the Sanders supporters will have to swallow theirs. And while they’re at it, they would do well to stop blaming Sanders for their own shortcomings. There is absolutely nothing preventing Clinton from siccing one of her Super PACs on Donald Trump right now. Obama, you’ll recall, didn’t wait till the convention to attack Mitt Romney.

As for Sanders, he has every right, as Hillary Clinton said in 2008, to make sure the “people who voted for me [are] respected and heard.” Especially when he keeps winning the battle of ideas. Only last week Clinton abandoned her longstanding opposition to expanding Medicare—and called for Obama to drop plans to push through the Trans-Pacific Partnership in the lame-duck session of Congress. Does anyone seriously believe either of those shifts would have happened if Sanders had quit?

 As Sanders said last week, “We share a commitment to electing progressive Democrats up-and-down the ballot in Nevada and across the country and are committed to soundly defeating Donald Trump and the right-wing Republican agenda.” Being less dismissive—and less heavy-handed—now can only help Clinton to enlist Sanders and his supporters after the convention. Not doing so risks bringing the kind of resentment—and chaos—we saw in Las Vegas onto the streets of Philadelphia.