A right-wing Republican presidential candidate Senator Sam Brownback, and right-wing Democratic presidential candidate Senator Joe Biden, have collaborated on a bipartisan bill to divide Iraq into three states. They call this 'Plan B', although a more appropriate title would be 'Plan 9 From Outer Space'. It's been floated by liberal-leaning intellectuals like Peter Galbraith, as well as former Carter assistant Leslie Gelb, and has been echoed by 'realistic' critics of the war in the British papers. The White House have not favoured this so far, despite the fact that their divisive strategies and patronage of corrupt Kurdish and sectarian Shiite groups are certainly likely to generate a weak central state, and despite the fact that the 'federal' constitution they have tried to impose does more or less divide Iraq into three. Note that the formal structure of a single country would remain in any event - no American politician wants to give a large part of Iraq effectively to Iranian control. But the central state would be weak, vulnerable to fracture and patrimonial corruption, and ultimately guided by the American embassy.
The wall in Adhamiya, which analysts say is creating de facto segregation, and which has already produced several local protests, is a crucial test for the American state. If they can use this formal sectarian lockdown to gain better control of the situation, then the Bidens and Brownbacks will probably have a better hearing in the NSC and other policymaking bodies.