These "Rockefeller Republicans" have not realized that the nation changed. The blue-blood political ideology was forged in the era of the New Deal when the nation was highly unionized, government was seen as the solution, and Democrats could actually be trusted with the defense of this country. All that has changed, and the "Rockefeller Republican" ideology, which successfully held the party together through the FDR years, must now be retired.
This is similar to the 1880's when the "Old Guard" Radical Republicans were pushed out by the industrialists.
The story now may be that some of the people Republicans have come to count on in the "blue states": Catholics, Evangelicals, younger voters, just aren't so keen on Bush or the party just now.
As the GOP becomes the voice of the "red states" it alienates some Northeastern voters. I don't think it's so much a matter of ideology as it is of style and personal affinities, but the administration's difficulties do a lot to make things worse.
One thing to bear in mind, though, is that in some states, like Rhode Island or Massachusetts, a regular party Democrat candidate may very well be more conservative on social issues than a Republican. So politics there can be more of a pick and choose, "vote the man not the party" affair than in other parts of the country.
OK. FDR
Name three more.