...”constitutionally qualified to challenge....
OK, lets see, what office or position would be able to issue a challenge under the constitution?
The person who signs the nomination eligibility sheet?
A member of Congress?
The other party’s nominee/the loser of the election?
AZ Gov Brewer
AZ Sec of State
AZ Attorney General
AZ electors (probably not)
AZ senators and house members who can object to the certification of the vote taken by the electors
The date, Jan 6, is mentioned by Gallup as the certification date AFTER the electors vote. If two congresscritters or two senators object to the certification (remember that Cheney buzzed by the call for objections and Pelosi did her jack-in-the-box number to Hail Obama to lead a cheer to drown out any objections) then...something of an investigatory nature can happen regarding eligibility, IIRC.