is the moderate one that's currently being purged?

I would think that the coming break-up of the Republican Party would be followed by a period of such utter Democratic dominance that after a few boring, lopsided elections, there would be growing pressure on the Democrats too, to split themselves into moderate and progressive wings.

That could lead to some very interesting political re-alignments, with perhaps the former moderate factions of both parties ultimately ending up together in a new party, and competing against the progressive Democrats on the left, and the Palin/Limbaugh rightwing former Republicans on the right.