I'm looking historically, not at the convention. Obama numbers are significantly lower than GW Bush (2004), Clinton (1996), and Reagan (1984) at this point in the cycle. Is it too low to win? Well, maybe or maybe not. I won't be looking until after the convention.
Is it really significantly lower than Bush? I doubt it is even lower than Bush to begin with. The difference is that Obama has a lot of downside possibilities while Bush didn't face that problem. If the economy stays fine, and we get 100k+ jobs numbers, Obama will win. I just don't know if that will continue.