Bush can nominate whomever he chooses. It's up to the Senate to confirm or reject the nomination. If they reject the nominees based solely on their religious convictions - and that seemed to be the case for the past several years - then they are in violation of the Constitution.

To ask a judicial nominee how he or she will rule on a specific issue - most often abortion - is to use a litmus test. Bush denies using a litmus test to select nominees but the Democrats have most definitely been using one in the confirmation process. However, they seem to stupid to realize that if the nominee answers how he/she will rule on a specific issue in advance, then when the issue comes before the court, he/she will have to recuse.

Spin that one however you please.