I assume your thesis then is that the Democrat party since 2000 has been moving fast and hard to the left..so the "leaders" have to follow the herd in order to stay in power.
That would seem to consign Dems to a near permanent minority status..given the conservative bent of the nation as a whole..
Obama said he wanted to "fundamentally transform America." He's working hard at it..but he may end up fundamentally transforming the Democrat party.
Logically, it would, but they keep moving the center further left.
Even five years ago, gay marriage was considered an extreme to leftward position with civil union or some legal equivalent the mainstream position even within the party. Now, if you don't buy the whole nasty package, your a right wing teabagger.
And too few of the Democrat rank and file even bat an eye because the enemedia herds them like sheep.