This reminds me of Fred Thompson. Back around last summer, many of us were anxiously waiting for him to get in the race, but the announcement never came, despite several hints. I imagine it was because he was waiting for that season of Law and Order to finish its run. Anyway, finally in September, the announcement came, but it was too late. The wave of momentum had passed him by and by then, too many people had made up their minds for someone else, and he just couldn't muster the support, despite his conservative views.
If Obama continues to tarry like this, it will only hurt his campaign further, and whatever bump in the polls that he may be expecting just won't materialize.