I've so far resisted weighing in on the Chait-Lindsey "liberaltarian" smack-down, mostly because Jon has done such a nice job rebutting the case for a liberal-libertarian alliance. But there's one claim that might be worth examining more rigorously given that Brink (whom I think is an exceptionally smart and thoughtful guy) keeps invoking it. It's the idea that there's some "economically conservative/socially liberal" center out there waiting to be captured by Democrats.
Granted, this idea might be intuitively appealing to socioeconomic elites--who, as Brink notes, exercise disproportionate influence over public opinion--since it reflects their own beliefs. But it's simply not true. Perhaps the most detailed data we have on this question comes from a Pew Research Center study that sorts the voting public into eight ideological groups. (There is a ninth group, called "bystanders," that doesn't vote at all.) Of the eight groups, only two can be said to have limited-government worldviews, accounting for about 20 percent of registered voters. Only three of the groups appear to have non-socially-conservative views, amounting to just over 40 percent of registered voters. (Only one group has overtly liberal social views.) And the number of groups with both economically conservative and socially liberal views is ... zero. (That's not to say there are no such people, just not enough to form a distinct group.)
This implies that roughly 80 percent of registered voters have moderate-to-strong support for government spending, and roughly 60 percent have somewhat-to-intensely conservative views on social issues. On top of that, Pew identifies three groups, representing 43 percent of registered voters, who are both economically liberal and socially conservative, giving old-line populism a very solid base on which to build. (Versus no electorally significant base for pure libertarianism.)
Brink invokes Bill Clinton--at least the neoliberal Clinton who served in the White House, not the populist who got elected in 1992--as a model for Democrats. But the implication of the Pew numbers is that a socially conservative/economically liberal candidate would beat a Clinton-style neoliberal any day of the week, setting aside non-ideological attributes like personality. I'd argue that Clinton won in 1996 because, in addition to being far more personally-likeable and charismatic than Bob Dole, he was the more economically liberal candidate in the race. (Incumbency also had its advantages.)
That is, Clinton won in 1996 despite his rightward drift since 1992, not because of it. Dole simply lacked the vision to identify his own optimal strategy, and he was too beholden to his party's libertarian wing to act on it even if he had. (Though, in his defense, the country as whole was slightly more libertarian back then.)