Why would he even debate McGrath? Is he worried that he might win by less that 20?
Remember that he did debate his last opponent, and wound up crushing her. Perhaps he wants to repeat the same feat with this opponent.
Grimes was competitive until the last month.
Grimes shot herself in the foot with her refusal to just admit she voted for Obama in 2012. Wouldn't have hurt her campaign because she was a Democrat, but her unwillingness to state the obvious just made voters sour on her candidacy. A poor debate performance against Mitch + the GOP tsunami that built the last six or so weeks of the midterm cycle finished her off.
Due to the anti-Democratic environment of 2014, Allison Lundergan Grimes would have lost anyways.
