The truth is that by the time that a party's voters become aware enough of what is happening that they shake off the pervasive political propaganda it is too late for them to do much short of pretty much just crippling the entire organization.
Remember the Tea Party movement? Before Obama colluded with RINOS to destroy the movement, almost half of their activities were aimed at controlling or getting rid of Romney and McCain style RINOs. The Dem Party, on the other hand currently does NOT have an internal watch dog group dedicated to preserving the essential essence of -- what it once MEANT -- to be a Democrat. Instead it has got radical Leftists interested only in increasing the radicalism within the Party.