In my opinion,[footnote]It should be noted that the board strokes of this are not uniquely my ideas, but do parallel with existing theory.[/footnote] there are fundamentally two kinds of candidates in a presidential primaries: actual candidates and issue candidates.[footnote]There's also a distinction between main stream and insurgent candidates which sometimes overlaps with this, but that's a discussion for another time and is mostly about optics and political style. There's also promotional runs that are designed to increase personal prominence, but that kind of falls into the issue candidate category even if one is our current president.[/footnote]
Actual candidates are fairly straight-forward: they're in the race with the intention of becoming the nominee and eventual office-holder. They campaign, fund raise, and try to portray them as disciplined enough to be worthy of holding the office. Both Clintons, Obama, all three Bushes, Romney, Kerry, Dean, Gulliani, Cruz, Gabbard, and Buttigieg are all good examples of Actual Candidates and most candidates are going to fall into this category because most candidates want to win the office (you generally don't campaign for an office you don't want).
Issue candidates are in the race to make a statement and try to have a debate on their pet issue(s). Think Andrew Yang (UBI), Ross Periot (National Debt), Lawrence Lessig (Election reform), Ron Paul (Libertarian economics and regulation) (kind of), and others who usually fade into obscurity fairly quickly. They tend to have anemic fundraising or self-finance, and their primary goal is to qualify for the debate stage in order to promote their ideas and force actual candidates closer to their ideals or at least force a response to them. Most of them know and some will even outright admit that their candidacy is generally a futile effort.
Here's the thing: Issue candidates usually stay small and tend to don't lead their supporters on when reality hits and they have to end a campaign. Meanwhile, actual candidates tend to do everything they need to to win, because their volunteers and voters believe they will be the one best suited to win the general election (why they believe that varies heavily even within campaigns) and, to put it bluntly, it would be a betrayal to not try to win.
Sanders in 2016 is an interesting case that is not particularly unique (particularly in down ballot races where single-issue stances can get you through a primary), but relatively uncommon in a presidential primary. He started out as an issue candidate in 2015, largely based on an small base of support that expanded when Warren declined to run in 2016 against Clinton, making him the only outspoken liberal on the stage when a lot of progressives still disliked her for a myriad of reasons that largely have their root in the 2003 Iraq War Resolution.[footnote]It should be noted that Clinton's positions and voting record put her decidedly to the left of the party leadership as 75% more liberal then other Democratic Senators [https://voteview.com/person/40105/hillary-rodham-clinton], though she campaigned as a center-left establishment leader for the party.[/footnote]. Because a lot of potential presidential candidates did not want to run against Clinton or felt that they would almost certainly lose against the undisputed favorite for 2016 [https://news.gallup.com/poll/181988/hillary-clinton-clear-leader-favorability-among-democrats.aspx], you had a relative dearth of candidates in that cycle, with only five qualifying for the first debate in October 2015, all but one of which (Governor Martin O'Malley) dropped out before Iowa, with him dropping out right afterwords. After that, it was Clinton versus Sanders for the rest of the Primary, making Sanders the de facto vote if you didn't want Clinton for whatever reason you fancied. After a de facto tie in Iowa and a large victory in New Hampshire, the notion of a Sanders nomination was suddenly no longer a pipe dream and he eventually ended up with the campaign infrastructure of an actual candidate with the message of an issue candidate. He lost in the end, mostly due to very poor performances in Southern states and being overly reliant on Caucuses to win larger net delegate gains, but would enter the 2020 cycle as an undisputed actual candidate.
So why am I talking about this? The point is that Sanders knew he was going to enter the race as an actual candidate, which means he needed a plan to secure the nomination. His plan, as he put it, was to secure the nomination by increasing voter turnout among the young and infrequent voters that rarely turn out in large enough numbers in elections and primary elections in particular. While I have qualms about this strategy, it was a theory that could at least be tested in the actual primary elections. And for the most part, it failed. Iowa saw no substantive change in turnout from 2016 to 2020 [https://nymag.com/intelligencer/2020/02/why-wasnt-turnout-better-in-iowa.html]. New Hampshire turnout was increased [https://www.vox.com/2020/2/12/21134438/new-hampshire-democratic-primary-turnout], but it didn't translate into more than a de facto tie. Nevada was the only state where record turnout translated into electoral success [https://www.vox.com/2020/2/23/21149443/nevada-caucuses-2020-turnout-record], largely thanks to Sanders' outreach to the Latinx community that has a tradition of organizing and economically progressive positions and a splintered field of alternatives.
But South Carolina came and the indicators of a problem started to emerge. He lost the black vote by a wide margin. He didn't break 50% with black voters under 45 in some states [https://fivethirtyeight.com/live-blog/super-tuesday/]. Youth turnout remained relatively low [https://www.vox.com/policy-and-politics/2020/3/4/21164479/super-tuesday-results-exit-polls-turnout-patterns]. His strategy was not working.
Here's the thing: if you're an actual candidate for the presidency, and particularly if you're a top-tier candidate, you have a massive operation filled with volunteers and supporters, a large warchest of money from donors big and small, and a small nations' worth of manpower doing what you tell them (explicitly and implicitly) to help you win, both within the campaign and outside of it. That comes with an immense responsibility to use those resources in a manner that helps you win the nomination and general election, because every dollar you get, every volunteer hour spent, and every vote cast for you is a sacrifice someone else made because they believe in you (whether passionately or, in my case, in a disgruntled manner) and in your ability to win. An actual candidate has a duty to try to win until the facts say that it is reasonably impossible to do so. And for the vast majority of primary voters, they're not going to vote for someone who they don't think can win in November [https://thehill.com/hilltv/what-americas-thinking/444295-poll-democratic-voters-prioritize-defeating-trump-over-their].
And that is why I'm so frustrated-to-infuriated with the way the Sanders campaign operates and, in particular, communicates. There's nothing in his strategy that required him to paint most of the party as against him as he often did in campaign rallies and media appearances, even if it was true in the sense that moderate/establishment-lane candidacies were his opposition. There's nothing that required him and senior staffers to appear on a sexist and bigoted podcast [https://www.vox.com/policy-and-politics/2020/3/9/21168312/bernie-bros-bernie-sanders-chapo-trap-house-dirtbag-left]; there's nothing that required him to tout the endorsement of one of the most prominent non-Republican bigots in the country [https://www.vox.com/policy-and-politics/2020/1/24/21080234/bernie-sanders-joe-rogan-experience-endorsement-controversy]; there's nothing requiring him to endorse (and have to walk back) a blatant sexist for congress to replace a queer woman [https://time.com/5749887/why-bernie-sanders-walked-back-his-endorsement-of-cenk-uygur/]; there's nothing requiring him to have a parade of surrogates who can't seem to stay on message (and yes, if Talib is a surrogate for Sanders, it means not alienating the near-17 million potential voters who voted for Clinton in the 2016 primary [https://en.wikipedia.org/wiki/2016_Democratic_Party_presidential_primaries#Schedule_and_results] no matter how much it's justified, because you need every vote); it means dropping or obscuring or disavowing or conditioning things that you support or identify or said if they're unpopular with key voting groups; it means registering as a Democrat like you're asking a bunch of your voters to do in states with closed party primaries and the party you're asking to lead. Every single one of these items and more makes it harder and harder and harder for a voter to support his candidacy. Why should a rank and file voter who identifies as a Democrat and might like or, more often, just generally favor Sanders policies over others throw in with a campaign that doesn't seem to care about winning if that's your top priority and he doesn't seem to be positioning himself to unify the party?
For all his faults and gaffs and shitty shitty shitty voting record, Biden actually did know the top priority of the majority of the Democratic electorate: defeat Trump. That's how he announced his campaign, and for decades of terrible votes and policies, his ability to bring rivals on board his campaign sent the message he's about unity and electability. He got the math guy who supported Sanders in 2016 to essentially say Sanders had lost [https://www.politico.com/news/2020/03/10/andrew-yang-endorses-joe-biden-125317]. Sanders got failed 1984 and 1988 presidential candidate Jesse Jackson [https://www.politico.com/news/2020/03/08/jesse-jackson-backing-sanders-123747]... after blowouts in Super Tuesday and probably too late to dramatically alter the results of the March 10 cluster.
And Trump is right about one thing: people like winning. They don't want to support someone who they think is going to lose whether they're a shrewd political figure trying to capitalize on the campaign or a voter who is trying to decide who they want to support. The Bandwagon effect is real and losing is embarrassing and disheartening. Sanders was riding high after Nevada, but he should have pivoted right away to a unity message, toned down more divisive rhetoric, and reached out to center-left figures who might not have been completely on board with his message, but could give the impression his coalition was growing and make it seem like he was going to be the winner to beat without appearing like a massive threat to the rest of the party.
So while I support him staying in the race after Tuesday, I suspect that by this time next week that gap between him and Biden is going to get a lot wider unless he can pull a serious turn-around in delegate-heavy Florida [https://www.realclearpolitics.com/epolls/2020/president/fl/florida_democratic_presidential_primary-6847.html] (everybody loves an undergdog), I suspect at that point the campaign is going to be done even if there's enough delegates remaining to technically get the nomination.
And if that happens and the math becomes inescapable, he should suspend his campaign and try to unify the party. That's the final duty of an actual candidate: when it becomes clear you will not win the nomination, you do what what is needed to make sure the person who will carries your supporters and the policies that they prefer to as close to fruition as possible. Because presidential primary elections are not policy debates, they're debates on who is best positioned to make those policies into law in a system where the president can block every priority that doesn't have a 2/3rds vote in both houses. Every dollar spent, every door knocked on, and every shred of hope that is invested after the point where victory is all but impossible is wasted in pursuit of vanity over substance, wasting it when it could be put to better use in the general campaign, down-ballot campaigns, or outside activities. And if you're more aligned with the likely winner than the opposing party's likely nominee, every day longer in an unnecessary campaign can actively harm the candidate that likely will be most likely to get your policies to reality, as it reduces the time that you and the other candidate can unify disparate internal voting groups to minimize losses.
And while Biden may say he doesn't support XYZ policy, do you really think the man who is claiming he's the guy who can "get things signed into law" is going to turn down signing a progressive bill that makes it through the deadlocked nightmare that is the US Congress even if he has qualms about it? I doubt it. That's why its so important to reach out and play the give and take of politics: endorsements today turn into congressional votes for priories tomorrow. But none of that matters if you don't win. So if it becomes clear that Sanders can't win, his best bet to getting the policies he claims to support is to get Biden onboard and lock him into prioritizing (or at least not blocking[footnote]a presidential stance on a policy can actually make it harder to pass [https://www.brookings.edu/research/going-partisan-presidential-leadership-in-a-polarized-political-environment/], which suggests moving progressive policy through the congress quietly can actually be more effective than presidential leadership.[/footnote]) items like Climate Change legislation, Student debt relief, regulatory reform, gun control, tax increases, etc.
So I feel Sanders has a duty to his supporters to do what he needs to to either win the primary or, in the now-likely event of failure to achieve that goal, position himself and his supporters in the place best suited to bring those policies to a reality, which will be by helping Biden win the general election and focusing on down-ballot races where money and organizing can make a real difference. But his theory of how he was supposed to win failed because those groups didn't turn out in the numbers needed to win more delegates, and when turnout did jump high, they voted Biden almost every time. Sanders is right that he represents the future of the Democratic party in terms of policy priorities (though not likely in tactics) and that youth voters do support him over Joe Biden. So Sanders needs to figure out a way to make sure those policies are most likely to come to fruition, whether that's through building his primary coalition to win the primary or helping Biden in the general, because you don't get policy into law without victory first.