For any nominee who would be worth it, the GOP does not have the votes.
There are 55 or 56 hard baby-killing votes in the Senate as it is now constituted, and nothing you or I or Frist or Bush says or does can change that. There is zero chance-ZERO-that any person who does not swear allegiance to Roe v. Wade, convincingly, could be confirmed by this Senate.
The baby killers will never allow a prolife Souter, they are too smart and their opposition research is too diligent.
Only the election on 11/2/04 can do so. Talk of "going nuclear" is just bluster, Frist most certainly does not have the votes.