While I too am a bit puzzled as well as nervous about the parade of liberal Obamaphiles (er, moderators), I’ve been thinking of one possibility that this could really work out in Romney’s favor....
If he can successfully work with or around the liberal bias, or cut the moderator down after calling them out, and come out of liberal-bias debates as the victor, it only stands to make him look like a much stronger candidate, and especially one who can stand up for himself while working with Democrats, which would speak well about working bipartisanlly as president.
Just my $0.02
This worked very well for Bush 41 in 1988, when he ambushed Dan Rather. Rather was laying for him with a "gotcha" question, but the Old Man turned it around and incinerated Our Man Dan -- I don't think he ever got over it, and it may have played a big part in his self-destruction in the document scandal that he tried to gin up against Bush 43.
The Old Man touched him up, and Junior polished him off. Can't think of a nicer outcome.