Is it Franklin Graham's job to judge who is a Christian?

Billy Graham’s son, the Rev. Franklin Graham recently said, “I don’t know…” if Obama is a Christian. He’s enthusiastically endorsing Rick Santorum because he IS a Christian. Did Jesus rescind his command to “Judge not, that ye be not judged” and just forget to come back and tell us about it? Did he appoint Franklin Graham his sole judge on Earth, or perhaps the Republican Party? If so, I sure didn’t get the memo.