"Just to clarify..if a Democratic senator did what Craig did, I'd think he would probably resign also...and that most other Democratic senators would likely 'help' him make that decision."

You may think that, but history does not bear it out.

Republicans who have left in sexual scandal:

Foley
Craig
Livingston
Bauman

Democrats who have left in sexual scandal:

__________________
__________________
__________________

Democrats who have survived sexual scandal:

Clinton
Studds
Franks

Republicans who have survived sexual scandal:

________
________
________

It's not playing out the way you claim it is.