The "Nuclear" Option

I understand that the Senate is a deliberative body that moves slowly, and most of the time I appreciate that, as I see most of the legislation that comes from Washington to cause more problems than it solves. However, as I have said before, judicial nominations deserve to be voted on by the full Senate, period.

Therefore, I don't understand the reluctance of the Republicans to employ the nuclear option, barring nominees from filibuster. In my view, filibustering nominees in itself is nuclear, so why the timid approach? Arlen Specter, of course, is one reason. With Republicans like him in positions of power, it is a tenuous majority indeed.