I've been wondering about this all day. Doug looked like he'd just been dumped by his first girlfriend and never saw it coming. My guess is the party told him he wasn't welcome and, thanks to his egotistical ways, couldn't believe/understand the rejection. Or, perhaps, he finally clued in that he messed up, big time. Whatever the case, I don't think Doug made his announcement because he wanted to. If his true ambition was to run Rob's campaign, he would have been breathing fire, not looking like someone with a wedgie.