Even this center-right has been stiffed by this administration, which has taken domestic policy decisively to the left. And if the right doesn't have enough votes to elect a President, the elitist country-club Rockerfeller/RINO wing of the GOP definitely can't. Yet, through this President, they rule anyway.
dingdingdingding! I'm not voting to give the reins of power to a John McCain or Rudy Gulianni.
Moderates are irritated with Bush for pandering to the far right.
Given the economic conditions when he entered office, plus the shock of 9-11, Bush's cut taxes-increase spending was the right policy. Moderates recognize that Bush used this successfully and that his attempts to subsequently cut spending has not been accepted by congress.
You are correct that moderates cannot elect a president by themselves. We would prefer to make a compromise/deal with the far right. But if you don't want to make a deal, we will make a deal with the middle.
You, otoh, have no one to make a deal with except us. We don't need you, you need us.