I wrote a little while ago about how the Republican Party had an advantage because it was more willing to replace its leadership. It ocurred to me today that this may be because the Republican Party still has a core set of principles, however unhonored in the breach they may be. This provides a standard against which to judge the leadership and justify the removal of the non-performers.
The Democratic Party, on the other, has lots its core principles to a changing world, those having become either outdated (e.g. civil rights) or proven wrong (e.g., welfare state). That leaves only money and power as the keys to the leadership and naturally long timers will have a massive advantage on those points. Is the ossification of the Democratic Party leadership simply a side effect of their loss of ideology?
One also notes that the only serious challenge to the leadership is the hard left Internet faction and that their challenge is not based on a superior ideology but purely on the ability to organize and raise money. It shows that in the long run, it is ideas that have consequences.