I don't think that the Republican leadership is "pandering" to moderates, I think it is paying them lip-service. Once Bush is reelected they can work on satisfying their base.
You are right though, they do have risk alienating the base. This just means they are walking the election year tight-rope right now. Since there are only two real meaningful parties any split is disasterous and the Republicans know this. They won't move too far to the left, because they don't want another Ross Perot spoiling things. Just as the Dems won't move too far to the right and risk another Nader taking votes.
All I'm trying to say is that I wouldn't worry that the Republican party is moving too far to the left. After election day there won't be any more need to appease moderates for another four years.
I believe GWB sees himself as president of ALL Americans, not just one party or one interest group. Like all politicians I suppose he has to take care of his big donors first, and of course he wants his base supporters to vote for him, but he also has to govern. And that means governing all America. Not just the red states but the blue states too.