1) Chances of an an investigation uncovering fraud leading to a possible re-vote.
2) Failing that, Chris McDaniel's chances as a write-in candidate.
Unfortunately it wont count if people do write him in.
http://www.tmcnet.com/usubmit/2011/01/16/5247199.htm
According to state law, write-in candidates are permitted only as the legitimate substitute of a candidate who has died, resigned, withdrawn or been removed from the race.