This issue was discussed in detail on the following thread. I am linking one senario and noting a second post of a differing senario. They make for interesting opinions of what might happen but I have no idea how they would play out if it really gets to a court hearing.
Post 202 and then skip down to post 211:
http://www.freerepublic.com/focus/news/2129827/posts?page=202#202
Thanks for that link. Very informative. As Congressman Billybob explained in his post 211, I thought that a challenge to the qualification of a candidate can come from an Elector of the Electorial college. I hope it would not be left up to a Democrat controled congress.