Maybe it's a Rovian move on his part: support the blithering ineffectual completely insubstantial village idiot (which is saying a lot in SF) in return for a little Dem support. I can't fault him for that.
Feinstein does have some streaks of sanity. Every now and then she's like a stopped clock twice a day. The same can't be said of that of the ultra-socialist Boxer.