He doesn't care. The second he becomes chairman, he is not responsible to anyone for five years. He can torpedo Bush at will without consequence. The chances are the president won't be able to get a single nominee on the Supreme Court. Hillary Clinton will probably pick the next 5-7 Supreme Court justices.
I'm really pissed at Specter, but no one is going to stop Bush from putting his people on the court. He's going to nominate an Hispanic, and the Dems will be scared to death about voting against him, or even criticizing him after what the Hispanics did to them in this last election.
I suggest that we start with Gonzales, then maybe Martinez, then go back to Estrada. The Dems blocked Estrada from serving on the DC Circuit because they were afraid it would be a springboard to the Supreme Court. Make them pay by appointing him to the Supreme Court anyway.