Jackie supports Dunbar now. She actually found Dunbar admirable and went to her for free. Before she was asking for cabinet positions.
I couldn't remember where she ended up, but yeah see that she went to Dunbar. I think it's more about hitting back at Frank. It also seems to have been a result of the situation with Remy (she basically wanted him and then when he shunned her she wanted to get away).
It has to be Stamper then. The ONLY person who can link to Frank's downfall is Stamper. All the murders and etc, it's all untraceable now.
It has to be Stamper's betrayal. It can't even be anyone else even if the show tried.
That's true if that's how they plan to make his downfall the result of that (which seems obvious since I don't see why they'd have kept those lines running otherwise, and especially the emphasis on Doug in season 3), but that doesn't necessarily have to be how it happens (I personally hope it's not as I think that's been fairly junk from almost the get go). Claire alone could take him down, and I think there's others that could as well. With how it's setting up, it actually seems like it's going to be a huge letdown. They built up the progression and the characters and now it's like they're just pushing them down to low level political and personal BS. Which might have been their intention from the start (i.e. House of Cards can crumble from small things), but with the spectacle they were building up it's a disappointment.
Stamper doesn't actually know that Frank did that stuff though does he? Only thing he can actually do is say that Frank had involvement with the people (and actively did work to ruin Russo) and told him to take care of Rachel, but that will be the worst route for him. Basically he's in a no-win situation with that as he can't really let anyone else know as anyone that uses that then he'll get the worst of it.