David Brooks certainly isn't wrong to suggest that the programmatic unity Democrats are evincing in the primary isn't likely to escape an actual administration unscathed. But he's vastly overestimating the size of the domestic divisions. The policy priorities of the traditional leftists and the traditional centrists are, by and large, the same. The Rubinites realize their open markets and dynamic capitalism is endangered by broad feelings of economic insecurity, which can then be expressed in a Dobbsian roar against immigrants and trade. So they want universal health coverage as much as the lefties. In general, Jacob Hacker's view that the defining domestic problem is economic insecurity -- and it stands in the way of both a just and dynamic economy -- has taken hold across the party, which is why Hacker has published with the centrist Hamilton Project and their sworn enemies at the Economic Policy Institute. But if the question will not be of policies, compromises can still divide the party. If a Democrat ends up bargaining away the public insurer to achieve the plan's passage, will the left feel betrayed, or accept that as a pragmatic compromise, and a decent first step? On Iraq, however, Brooks is speaking the truth. It doesn't look to me like either Obama or Clinton will pursue a particularly quick withdrawal strategy -- they've been careful to avoid any hard and fast promises in the primary (remember when neither could promise to have all troops out by 2013?), and that's facing an audience and electorate much more maximally oriented towards withdrawal than anything they will see in the general election. Their hesitancy to end the war could create substantial anger on the left. If Clinton continues the war, I think you'll see the Left turn sharply against her. If it's Obama, I think you'll see them work harder to rationalize his position as pragmatic, and let his principles stand in for his program. Folks forget that in 2003, Howard Dean was opposing the war while suggesting a policy not far off from the Surge. "I believe that we need a very substantial increase in troops. They don't all have to be American troops. My guess would be that we would need at least 30,000 and 40,000 additional troops," he told Tim Russert. Yet he was still the anti-war candidate. Today's conversation is more sophisticated, and Obama isn't going to start a new surge. But it'll be important to see whether a candidate they philosophically agree with is enough to distract the Left from policies they may oppose.