[T]here are actually two groups of "centrist" voters who matter in general elections: 1) upper-income social moderates, who own stock and favor balanced budgets and free trade, but who also favor abortion rights, affirmative action, gun control, and some forms of civil unions or gay marriage. And 2) culturally conservative blue-collar voters, who worry about health care and the loss of American manufacturing jobs, were strongly supportive of the war in Iraq, oppose gun control, are at best lukewarm on gay marriage, and have a cultural (if not economic) suspicion of big government and the far-away "Warshington" elites who run it."Etc." then goes on to explain how various Democratic presidential candidates fare among these centrist groups, as well as among the party's left wing. (Matthew Yglesias concurs with this analysis.)
Well, the world is catching up to me, but isn't quite there yet. As I explained long ago, the two middle-class groups identified by "Etc." are not so much "centrist" as in transition, rapidly evolving into the core constituencies of the two wings--and parties--dominating American politics.
The current administration's policies are tailor-made for the latter of the two groups, right down to the profligate government spending and (at least rhetorical) concessions on health benefits and protectionism. Were it not for the Democrats' strong peacenik contingent, it's a fair bet that the libertarian types who would have been solid conservatives on economic grounds during the Reagan years would now be defecting in droves to the Democratic Party.
The main Democratic presidential candidates, on the other hand, are for the most part crafting a message that appeals to the other supposedly "centrist" group: socially libertarian, hawkish on the deficit. And the "traditional" post-sixties left is falling into line, embracing heroes like Paul Krugman who rail against government profligacy like some latter-day Hooverite gold-standard advocate.
Unfortunately for Democrats, the left's continued unstinting loyalty is the party's downfall, dooming its loyalists to second-place status as long as they remain wedded to a dovish foreign policy alignment. If they could only see fit to embrace a more assertive national security agenda, it's likely that their pro-small-investor economics and social libertarianism could pry loose many more of their natural upscale constituents from the Republicans, and help them regain their nationwide competitiveness.