It was sad when DeMint left the Senate, he had integrity which is sorely lacking amongst most.
I don’t remember the democrats promising to give Lieberman his assignments if he won his independent bid. But they ended up doing so anyway, and he pretty much stayed democrat.
This was one of those early “establishment” attacks on the conservative candidates, and one of the more egregious, although given Lisa’s record it could be they were more scared that she’d switch to the democrats (at the time, they actually thought they’d win control of the senate, while stabbing conservative candidates in the back).
Or it could just be the obvious, the establishment of the GOP more aligned with the democrats, and like the democrats, focused on always defeating efforts to move the nation away from liberalism.
It is what they have done for generations.