Really now. This is not a whole lot different from the Republican Party's treatment of their 2010 nominees in New Jersey, Nevada and Alaska. In fact it is damn near the same. The parties expect party loyalty (above all else) and will not take much deviation from the party line. Especially a deviation to the right.
That’s the dirty little secret they’re trying to keep hidden. For all the “Moderate” holier than thou lip flapping about compromise and electability, they themselves are the ones who don’t compromise with conservatives, ever.
Compromise is reserved for their friends on the left.