Looking back in history, the Rockefeller Republicans chose their course because they believed their party could not beat New Deal Democrats except by moving some distance toward their philosophy. And in particular, they believed they could not beat Democrats in New York, which in the first half of the 20th century was both the nation's largest state and one of the politically most marginal.
But by the early 1960s, New York was no longer the nation's largest state and was safely Democratic. And by the early 1970s, Americans were no longer voting for big government. The Rockefeller strategy was rendered obsolete.
It's not clear that the Clinton New Democratic strategy is similarly obsolete. Clinton calculated that Democrats could not win except by making inroads in the South and by making big gains in the suburbs. That's how he won twice, and Obama improved on his leads in the suburbs and carried three Southern states with Northern-accented suburbs (Virginia, North Carolina and Florida).
But Obama ran well behind in eight Southern-accented and Mountain states that Clinton carried in 1992. And polling now shows Democrats weaker than Obama was in 2008 virtually everywhere except in university towns and the affluent precincts of metro New York, Los Angeles and San Francisco.
Similarly, in Britain polling has shown Brown's Labor party holding its traditional redoubts in declining industrial towns but getting shellacked in the affluent suburbs where Tony Blair's New Labor thrived.
The left parties have reacted to their unpopularity by playing the race card. Democrats have tried to portray tea partiers as racist, and Brown called a lifelong Labor voter who questioned his policies a "bigoted woman."
Blaming the voters is the last resort of a party in trouble. Old Labor and the Obama Democrats may not yet be finished. But they're not doing as well as their "third way" predecessors.