Once the Senate passes amendments to a Bill, there is no "clean Bill" on which to vote.Not quite correct. This same bill was introduced at least three different times as S 659, S 1805, and S1806.
My point is that once an amendment has been agreed to, the possibility of someone standing up and saying "hey! remember the unamended bill!?! Let's return to it and pass it!" are virtually nil.
I realize that other incarnations of an amended bill can be introduced.