Why couldn't Voinoivich abstain from voting???
Because for whatever reason he had decided he wanted to publically embarrass Lugar, Republicans and stab the base in the back. Why no one knows. Warning signal about Judicial filibusters? Does he want more pork? Special pet legislation? Only can guess. Personally I wuld deny him everything.
It is quite a feat to eclipse McCain, but Voinivich has done it. Even McCain hasn't humilated Republicans in this manner.