I don't think they "seized" control. I think the Dems were complicit in the takeover. Most Dems are control freaks. Moving the Democrat party to the left, to a more Totalitarian organization, simply appeals to that kind of person.
Whether it's Nancy Pelosi, or the garden-variety Obama voter; they all know, in their perverted little minds, that the world would be a better place, if they could just control everyone else.
Why would anyone want to be in charge of a big pile of crap? That’s all that will be left when they’re through.
I will never understand how those people think.