Of course there are institutional factors. Money, lobbyists, a corrupt and broken political system. But these are only proximate causes. In the end, at the moment of truth, there must be something in leaders themselves that causes them to give up on the act of leadership at the moment when it is needed most. When people can win, succeed, flourish, there must be something in people to cause them to forego the gains that are almost so painfully in their hands.
I think you are too dismissive of this as a “proximate cause,” and may have mistaken the chicken for egg. Consider: money, lobbyists, and a broken political system serve as a filter that serves up an array of leaders from which people can choose. This has been famously illustrated by Lawrence Lessig by way of his Lesterland Analogy.
In other words, if you want to psychoanalyze Democratic leaders, you must first recognize that these leaders are not drawn from a random sample but, rather, are the leaders that have passed muster in the eyes of the oligarchy that funds campaigns and corruption. If you observe a trait they share in common, it is likely they were selected because of that trait. If you perceive spinelessness, it means spinelessness is a welcome attribute in the eyes of the oligarchy that gives us candidates from whom to pick.
If I may go full-blown cynic for a moment, I can say that the oligarchy behind Democratic Party candidates (some of whom are the same individuals and corporate institutions that are behind Republican Party candidates) greatly prefers weak moderate and centrist Democrats to strong leftist Democrats, so they would rather lose elections and lose in legislative battles with weak Democrats than back a strong Democrat that is opposed to the very political corruption that grants them the position of privilege and power they have.
It does feel like this has to change. The corruption and influence are so brazen and out in the open now, that it isn’t just the staunch cynics who say “it doesn’t matter who you vote for because they’re all bought and paid for” anymore. It’s plain for everyone to see. Now it falls to the voters to demand leadership qualities from candidates that the oligarchy has been trying to keep at bay.
It is time for people to look past who is the slickest, best-financed, most-connected, most-experienced candidate and pick one that actually represents their interests, which probably also means picking the one with legitimate leadership qualities and the spine to implement positive change. It’s a whole new paradigm, and some voters may not even know how to cope with the idea their vote can go to someone who isn’t a total scumbag, but it is something I hope they can warm up to.