I contrast this with what one of the senior architects of the Obama re-election campaign told me in the summer of 2012:
He said, "toward Labor Day, the poll numbers will narrow. Don't panic. It is a pattern, and it is not indicative of impending doom. We will tear our hair out over it so that you don't have to."
i.e. Very experienced and not at all overconfident. The day I met with them was also the day I met with Obama for an hour, and he seemed upbeat about his chances for re-election, but was not at all acting so cocky that he thought he didn't have to do anything because it was already in the bag.
I have no idea who will be the Democratic candidate to face Collins, but I hope it's someone with good stage presence and thinks quick on their feet. We bought a false (to some, anyway) good impression, ignored the perils, and are now paying for our haste. Now is the time to bring in the "experienced and not overconfident" team. Collins hasn't gotten any better. We just have to present someone who is.