I did a rambling, unfocused, "y'know"-ridden pre-Thanksgiving Bloggingheads with Matt Yglesias, in which among other things we discussed the way the Obama Administration seems to uniting realists, liberal hawks and progressives under a single foreign-policy tent:
As you can see, we both agree that this is probably an unsustainable state of affairs, but it's interesting to speculate about which ideological camp might drift back into the Republican Party over time. The easy answer is the realists - that's where they mostly came from in the first place, after all. But of course there's also a sense in which a certain kind of liberal hawk has more in common ideologically with a certain kind of neocon, on foreign policy questions at least, than realists and neocons have in common with each other. This is where the whole McLieberman notion came from; it's why Matt can write, plausibly, that, "on foreign policy, traditional Republican realists have a lot more in common with liberal Democrats than either do with Democratic hawks"; and it's why the following analysis from Michael Goldfarb has a lot going for it:
The liberal internationalists, led by Hillary, will also be a powerful force in the new administration, and in their battles with Obama's realists they may find willing allies among the neocons on the right. After all, liberal internationalists have been allied with out-of-power neoconservatives before, most notably during the fight inside the Clinton administration over U.S. policy in the Balkans.
On the surface, then, a long-term political sorting along Goldfarbian lines - with realists and progressives, both chary about committing U.S. troops abroad, associated with one political party, and liberal hawks and neocon hawks in the other - makes at least as much sense as the traditional progressives/liberal hawks versus realists/neocons alignment. But only on the surface. Ultimately, the two parties' foreign-policy elites need to map onto the two parties' domestic constituencies, which is why the McCain-Lieberman idea was a political non-starter: Yes, neoconservatives can cooperate with liberal hawks on specific issues, but they can't permanently share a political coalition, because on most other fronts liberal hawks are, well, liberals and neocons are conservatives.
True, some liberal hawks have a weak enough attachment to liberal domestic-policy goals to be comfortable shifting over into an essentially conservative coalition, just some neocons have a weak enough attachment to conservative domestic-policy goals to be comfortable shifting over to an essentially liberal coalition if it seems more welcoming to their foreign-policy ambitions. But for the most part, liberal hawks belong in a liberal party, not a conservative one, even if it leaves them sharing a coalition with progressives who disagree with them about where and when the U.S. should use force.
Likewise, realists ultimately belong in the conservative coalition - or at least some realists do. It's of course possible to be a liberal realist, rather than a conservative one - someone with wants left-of-center governance at home and balance-of-power calculations abroad - and some of the realist-oriented figures who've migrated toward Obama probably fit the "liberal realist" description. But the conservative coalition ought to naturally produce realists from its ranks, for their sake and its own, because realism's cold-eyed pursuit of the national interest is the most logical and productive elite-level expression of the Jacksonian, don't-tread-on-me nationalism that holds sway among a large swathe of the conservative base. Neoconservatism can and should speak for part of the American Right, but it can't speak for the whole of it; it's Wilsonian impulses will always be a bridge too far for many conservatives whose instincts run instead toward "to hell with them" hawkery. This "more rubble, less trouble" tendency within the Right's coalition needs to be channeled in a constructive direction by the right-wing elite, or else it runs toward jingoism and folly of various sorts. And such channeling is a natural job for a potent conservative realism, as is the task of balancing neoconservatism's tendency toward hubris and unrealpolitik. But within the right-wing intelligentsia, at the moment, it's a job that isn't getting done.