I blame Vo for this bunnie since I was rereading The Right Rite - part 3 when Wesley suggest that Xander being President would be worst then Xander being a FED.

So what if after the invasion of LA the truth about Slayers, Hunters and the Supernatural came out. Of course Xander would become an American hero when they've learned more about what happened in Sunnydale.

So when the campaigning starts for the next election someone suggested Xander for President (see someone outside the Watcher/Slayer. Maybe as a joke)

Now America is tired of the two party system we have and want someone different and they want someone who doesn't want the job but will do it out of duty (This is how it was meant to be but now with have career politician)

Now if you get enough signauture you can have someone name added to the ballot or you can write in their name.

Now between the demons who can vote (they know Xander to be fair) and the human who are tired of the bad leadership we're had, Xander suddenly finds myself President of the United States.