Speaking coldly cynically for a moment, if he had just said he'll "ponder his future over the holidays", kept out of sight until after the Alabama election, then announced this through a staff member near Christmas, he'd have a better chance of this blowing over.
This could actually be used to Moore's benefit by arguing it's a liberal double-standard, everyone does it, etc. I realize usually only political junkies make such nuances, but how much do you want to bet Fox and Sinclair will play the holy hell out of this story and compare it to Moore's (i.e. minimize Moore's situation with prime whataboutery)? Add that to every "Christian" conservative blogger, FB poster, and activist in Alabama similarly going ape $hit over this....
Enough to bring wavering AL Republicans back home? Unlikely, but it might be the shot of adrenaline needed to bring Moore's campaign back to life on the operating table.
I think that most people have enough functioning brain cells to understand the difference between boorish, frat boy behavior and pedophilia.
Also, no Republican official asked from Franken to resign. It's pretty obvious to me that they didn't do that out of magnanimity. They are afraid that if the congressional sexual harassment can of worms opens, then it will be their heavily white male party that suffers the most.