Iraqi election results and a hypothetical question

[sam h]

We will not have results of these elections for some time. However, I have read several pieces around the internet that suggest the general contours of some likely outcomes that might be of interest:

1) The United Iraqi Alliance (religious Shiites) will have the largest bloc by far, but whether they will have a majority will be very close.

2) The list of Ayad Allawi, who some US officials had hoped might emerge as a potential prime minister candidate, is not likely to do well. Neither is Ahmad Chalabi's list. So the two most pro-US lists (other than the Kurds) seem to be doing poorly.

3) The Sunnis are voting for Sunni lists (as opposed to the secular pan-denominational lists of Chalabi and Allawi), but the split between a prominent Sunni secular list and a prominent Sunni fundamentalist list that is seen as the de facto political wing of the insurgency is unclear.

So Iraq will probably have four years of rule by religious Shiites, but whether they will need coalitional partners to form a government is unclear. The guy being talked about most for Prime Minister is the Supreme Council for the Islamic Revolution's Adel Abdul Mahdi, who is an economist.

Now for my question:

What should the US do if the new government asks for a withdrawal or starts taking steps towards a formal or de facto partition of the country?