If your goal is to make a political point then ranking a sitting president all time is useful, but frankly any group that ranks President Obama over Reagan is idiotic and not to be trusted.
In terms of ranking he also has the unfair disadvantage of the expectations game, if you compare him to expectations he would rank near Hoover except that he didn’t have you know anything near the actual accomplishments of Hoover before the presidency.
My own rankings of presidents is here but they are not numerical they are by group. I still think he has to potential to end up almost anywhere in the list because of the major crisis that he has to deal with. The trick is the results of many of them aren’t going to be apparent for a while, maybe even not until years after he is out of office.
I don’t care for this president, but it’s just not fair to try and rank his place in history right now. I’m too close to it and there are too many variables.
For example regardless of the reason for it the appointment of Petraeus could dramatically change things, if congress changes sides as is likely how he manages to work with such a congress can make a difference. We are still not even half way into his first term.
Do I expect positive changes? Frankly no, but that doesn’t mean the can’t or won’t happen. He is the president of my country and I want the best for my country, I don’t think he will bring it but I’d be very happy if he did.
When those historians rank this president where they do they once again create a set expectations that have great potential to be unmet. They serve him and the country very poorly.
Update: Smitty makes the same point I did
