Sen. Bernie Sanders is undoubtedly walking a thin, and often confusing, line. He's railing against the Democratic establishment during the primaries, but he has vowed to do whatever he can to help Hillary Clinton win the general election in November should she be the party's presidential nominee. Will Sanders' supporters follow suit and fall in line with Clinton? Fears that they won't have led to widespread criticism of Sanders' campaign from Democratic politicians and pundits, who think that the Vermont senator should be careful to avoid alienating his supporters from the party. The thing is, it's not Sanders' job to unite the Democratic Party. Rather, he set out to fundamentally change it.

Recent events, such as Sanders' response to disruptions at Nevada's state caucus, have certainly increased criticism against his supposed "divisiveness," but the critique is far from new. The Wall Street Journal distilled a common line of criticism back in April when it wrote about one of Sanders' prominent critiques of Clinton — that she, like nearly every other politician, takes super PAC money, and that this could compromise her commitment to average citizens. This essentially calls her trustworthiness into question, and according to polls cited by the Journal, a lot of voters don't perceive Clinton as trustworthy. This could deter voters in November.

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But campaign finance reform and not taking super PAC money are primary elements of Sanders' campaign and his lifelong politics. Expecting him not to campaign on one of his key positions is expecting him not to actually campaign. Campaigning is a candidate's job.

A couple recent developments have ramped up criticism against Sanders' campaign: the Nevada state caucus chaos and his support for Tim Canova, who is running for a seat in the House against Democratic National Committee Chair Debbie Wasserman Schultz. What happened in Nevada is hard to untangle. Members of the Sanders camp are mostly launching accusations of corruption by the state's Democratic Party in favor of Clinton. Party leaders denied accusations of wrongdoing. The state's party filed a complaint accusing Sanders delegates of inciting violence amid reports of chair-throwing and death threats.

Sanders said in response to the party's complaint, "I condemn any and all forms of violence, including the personal harassment of individuals." But many think that he didn't adequately disavow the alleged violence at the caucus.

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This criticism seems to stem from the idea that the remainder of what Sanders had to say on the caucus was somehow meant to excuse the violence, which is in no way clear. He said that the state lacked a "fair and transparent process," and continued: "If the Democratic Party is to be successful in November, it is imperative that all state parties treat our campaign supporters with fairness and the respect that they have earned." These words led the Tribune's Dana Milburn to conclude that Sanders is campaigning against the Democratic Party itself, and that this is great news for Trump.

It's hard to say for sure, when looking at the available evidence, whether there was disproportionate unfairness and disrespect toward Sanders' delegates in Nevada's clusterfluff of a state caucus. PolitiFact's report found a number of claims from Sanders supporters to be unsubstantiated, though it didn't address accusations that a vote to implement "temporary rules" was held earlier than scheduled, leaving some delegates out, and didn't address questions around the deadline for registering as a Democrat, which, according to John Oliver, was set for a date that had already passed.

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One could criticize Sanders for advancing unsubstantiated, or at least exaggerated, accusations of corruption here, but the idea that he's waging an irresponsible war against the Democratic Party which will turn voters away isn't quite fair. Obviously, the process at the caucus wasn't "transparent," as Sanders noted, evidenced by the widespread confusion surrounding what happened and why. Whether the specific allegations from his supporters are true or not, that lack of transparency in itself is unfair.

The idea seems to be that, even if something bad happened, Sanders shouldn't attack a state party because it's part of the Democratic Party. But Sanders wants a better Democratic Party. Although I agree that he shouldn't be playing up the corruption card unless more is proven, I object to the idea that he shouldn't criticize a state party for what was a messy, chaotic convention, which facilitated at least the suspicion of corruption.

Finally, the fact that Sanders is backing Canova has been turned into some kind of mean girl cattiness, seen as a petty slight against Wasserman Shultz, who is running for reelection to the House for Florida's 23rd district against Canova. Politico's Kristen East called it "a clear and intended affront to the Florida congresswoman" and went on to outline the history of bad blood between Sanders and Wasserman Schultz.

Canova is a progressive candidate who has given his support to Sanders. The idea that Sanders would only have endorsed him back to hurt Wasserman Schultz (and, through her, the party) out of some kind of personal vendetta neglects the fact that Sanders is not only trying to get himself the presidency, but also get more progressives into Congress as well — something he outlined in his statement endorsing Canova.

During a conversation about whether Sanders is hurting the Democratic Party, MSNBC's Andrea Mitchell asked his campaign manager, Jeff Weaver, what Sanders' support for Canova means for his standing with the party. Weaver responded to Mitchell's question by noting that Canova is himself a Democrat.

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And that really gets to the heart of the matter. Perhaps Milburn was correct, in a sense. Sanders is running against the Democratic Party as it is. His job in this race has been not only to run for president, but also to attempt to make the party more progressive. That means doing things like pointing out fundamental non-progressive elements of the political process and the party itself, like big-money campaign financing. It involves calling out the party itself if its processes are flawed. It involves endorsing progressive candidates for Congress precisely because they are not establishment candidates.

These are Sanders' responsibilities. It's not his job to unite the party. It's the party's job to give Sanders supporters a reason to be part of it.