Senator Sanders is shouting for Americans to wake up. The best candidate to make his agenda a reality is Hillary Clinton.
The problem with Sanders isn't that he's angry, old, Jewish, or a socialist. Those terms are often used in the European Union to disparage the Left, and it's interesting to see how they're picked up in the US. But the stereotype doesn't translate to US politics.
The problem is that he doesn't fit the part. Superficially, he's not telegenic enough for the amount of exposure candidates get in a Presidential campaign. That's not really the problem, either.
The problem is him, who he is. A party of one. Even with a million donors and cheering crowds, he's a party of one. That's what he's been for his whole political career. He caucuses with the Democrats in Congress, he's running as a candidate for the Democratic Party nomination. It doesn't change the essential defining characteristic that matters, and that he chose. He's a party of one.
It matters because in politics you can't accomplish anything by yourself. As individuals and, scaled up, in groups, collective power is the only way to get anything done. An individual or group that isolates itself from others nearby on the political spectrum is bound to fail. In a democracy, you need to build a majority and maintain it to win.
I see no evidence in Sanders' career as an Independent that he has ever tried to do this. Since there is no organized Left in the US, it must be hard for Sanders' followers to imagine what it would take to build one. Instead, they imagine an ad hoc assembly that will come together across the land on election day because they have a candidate who leaves no room for doubt.
I don't blame them for what they believe. I look at Sanders. He graduated from the University of Chicago with a degree in Political Science. Surely he must have learned what it would take to implement the ideas he professes. Yet, in his political career in Congress, he chose a path that made it very unlikely for his ideas to come to fruition. By remaining an Independent, a party of one, he did nothing to gain wider acceptance of his ideas, or to build a platform so that his agenda would endure.
The Socialism that Sanders professes doesn't match his record as a party of one, either. What is Socialism if not inclusive collective power? It's not a system of exclusion or separation of the self from others or by others. He couldn't put it into practice by remaining a party of one.
Unless Sanders is able to sit down for a long-form interview, where he's prepared to explain himself to the public without the usual recitations we've heard over and over, his campaign will be stunted, far short of the goals he needs to win.