The very basis of modern fundamentalist eschatology is that a politician of great stature will come and unify the world's governments, fooling the world into accepting oppression through enlightenment. The Antichrist is pretty much what the word sounds like - a false Messiah who offers the exact opposite of Jesus' message, a charismatic leader whose words mislead us to the brink of oblivion. It's a fairly common exercise in fundamentalist circles, theorizing that any charismatic leader is or could be the Antichrist.
Varied theories abound as to the background of the Antichrist, but they all rest on the idea of a charismatic leader arising from murky backgrounds to fool and dominate the world. Portraying Muslim supremacist multinational citizen Barack Obama as the Messiah of a new age plays right into the idea of fundamentalist worries about the Antichrist or his harbingers. It's yet another reason the "popular = bad" meme is being pushed by the right. The conservative Christian base is intrinsically wary of anyone who's popular with the "wrong" people (i.e., not them), and entirely willing to brand them as party to evil. It's a model of fundamentalist action as old as fundamentalism itself, and particularly relevant in light of modern Christianity's interaction with popular culture and mass communication.
I may be being a massive anti-Christian bigot here...except having read a lot of apocalyptic material from the Christian Right, I'm not.