In fairness to Republicans, here is a CNN article on how Barack Obama got elected for the State Legislature out of Chicago, and then for the Senate seat he now holds for Illinois.
Obama's First Campaign
Apparently he has an army of people who contest every signature on the ballots to disqualify his opponents and run unopposed. Even if the signatures were valid, by the time it was worked out in the courts the election would have been over.
By the way, this was a tactic used by the Democratic party in 2004 in an effort to keep Ralph Nader off of the ballot in several states. If you think Obama's the only one who would stoop to this kind of campaigning, think again.