I was thinking about the reason why you are not sure about Obama.
Right now, with our natural mind, we probably can not see much difference between him and other politicians.
A lot of them support the same issues.
However, this is something the Holy Spirit must give you insight about.
After all, I myself was not sure about him until the day before his election
And that is what I think others who have expressed the same
There was an black Egyptian who posted here after he was elected.
He was excited about Obama being elected until God told him to not pray for him
 
So, I think the answer to your issue re Obama can only be answered by direct revelation from the Holy  Spirit to you.
A download from the Holy Spirit if you will
No amount of back and forth discussion will convince you.
You yourself have to seriously ask God to reveal who Obama really is.
And don't be in a big hurry to get an answer.
 
As far as praying for him,well, ask God that too.
If God reveals that to you I am sure you will comply.