Barring some kind of catastrophe befalling Hillary Clinton, Bernie Sanders is not going to be the nominee of the Democratic Party for president of the United States. But can we call his candidacy a success? It may not be much solace to his most enthusiastic supporters, but the answer is yes.
We should begin by acknowledging that Bernie Sanders running for president was kind of a crazy idea in the first place. Unlike someone like Marco Rubio or Ted Cruz, who began running for president as soon as they hit the Senate, or someone like Clinton or John Kasich, for whom a presidential bid is the logical endpoint of a long career in politics, Sanders never seemed to have the White House in his sights. While he has managed to pass some worthwhile amendments here and there, as a lawmaker he's mostly been a gadfly, critiquing the mainstream from his perch on the left and trying to expand the range of debate. Given the fact that he wasn't even technically a Democrat until he decided to run, the idea of him becoming the leader of the Democratic Party was beyond unlikely.
My guess is that he understood that himself, although I have no way to know what he was thinking (and of course he'd never admit it if he did). Running for president this year probably seemed like a good idea because the limits of the field would allow him to garner a great deal of attention as the champion of the left; with Clinton having cleared the field of all but a couple of longshots, the opening was there for a more liberal candidate. He wanted to make a point — about particular issues, about the Democratic Party, and about American politics in general — and he'd never have a better opportunity. Given Sanders' age, it was also probably the last chance he'd have to mount a bid.
It turned out that his timing was excellent. Disappointment with the messiness of governing and the compromises of the Obama administration left many liberals receptive to a message of revolutionary change. After ignoring him for a while, the media eventually became interested in his unlikely success, and the prospect of a real race on the Democratic side. Before you knew it, a Sanders victory seemed like a genuine possibility.
Even if he falls short, Sanders will still have made his point, with a louder megaphone than he ever had in his decades in politics. More people heard his advocacy for single-payer health care, free college tuition, and public financing of campaigns than did in the entirety of his prior career.
And he has undoubtedly pulled Hillary Clinton to the left. If Sanders hadn't been pressing Clinton on trade, would she have come out against the Trans-Pacific Partnership? Possibly, but I doubt it. Would she be talking about taking on Wall Street and promising to appoint Supreme Court justices who'd vote to overturn Citizens United? Would she be championing a clear liberal agenda — even if filtered through an incrementalism Sanders supporters dislike — without him at her heels?
She might have, but again and again in this primary, we've seen Sanders setting the agenda. Even if Clinton doesn't reach the place where Sanders is, she keeps taking cues from him on what's important, then saying she supports something a bit less radical that is meant to achieve the same goals.
We can't know for sure whether that will translate into a more liberal Clinton presidency than she otherwise would have run, but there's no doubt that if she does get to the White House she'll be keenly aware of the desires of her party's base, including Sanders' supporters. And now, as the acknowledged representative of the party's left flank, he'll have more credibility (and ability to garner media attention) pushing her administration from the outside than he ever would have had if he had been just another senator.
And those young people Sanders brought into his campaign? Even if they're disappointed, and even if some of them might stay home rather than vote for Hillary Clinton, they've been brought into the process, engaged and excited by politics. For many of them, the Sanders campaign will be the formative experience of their political coming of age, and it will influence how they think about politics for years, perhaps even for their entire lifetimes.
So while he probably won't be president, given the place where he started, that isn't anything like the failure it is for a different kind of candidate. No one expected Sanders to get as far as he did — maybe not even Sanders himself. When the campaign is over, he'll have a lot of reasons to call it a success.