EPIC usually has an epic GOP-leaning sample, sometimes with more Republicans than Democrats.
Was also the case in 2008 polling:
End May 2008 EPIC poll: McCain+4
End June 2008 PPP poll: Obama+9
Final result: Obama+16
Agree but it was in may and june, before the financial crisis...
It was also during/just after the MI/Florida DNC seating controversy, which probably dragged Obama's numbers down in both states.
Good explanation of 2008. EPIC polls no other state, so we have only other pollsters to compare to.
