Some Republicans worried about the next election. Oklahoma's Governor, Frank Keaton, said that that may well be true but at least they would have stood by their principles. And that, my friends, sums up the Republican conservatives' quandary in a nutshell. Part of being a conservative is a belief that there is a right and wrong answer to every question, what Isaiah Berlin calls monism. Once you find the answer to a question, the logic of that answer must be followed to the bitter end.
Conservatives are incapable of doing anything else.
It is how they are wired. If, then, resignation is the answer in a given case, then resignation it will be, because by your example you will show what it means to stick by your principles. Unfortunately for Bob, the point seems to be utterly lost on Bill. In fact, Clinton has said repeatedly that he will never resign. I think the resignations of Newt and Bob both stem from mettle fatigue.