With the stated aim of last week's UN resolution limited to the cessation of violence against the Libyan people – and an ongoing row over whether targeting Colonel Gaddafi would be legal – the Western powers are increasingly aware of a result that falls some way short of regime change: partition.
Conscious of the fragility of public support, and concerned about the mounting costs of the campaign, some members of the alliance against Gaddafi see merit in the idea. Yesterday, Nick Harvey, the minister for the Armed Forces, told the BBC partition was "one possible outcome". He added: "A stable outcome where they weren't killing each other would in a sense be one way of achieving the humanitarian objective."
Any informal partition would solidify the division that already exists in the country. For the rebels to survive, they would need to take settled possession of Ajdabiya, as the city controls the irrigation systems that supply water to their stronghold, Benghazi.
But any such plan would be fraught with complications. There are cities in the west of Libya where rebels have acted against Colonel Gaddafi, and there is no clear way of ensuring those rebels' safety.
There is also no sense that either side would accept a more permanent split. It is not clear how any division would be policed without Western boots on the ground – although Mr Harvey refused to rule it out. And there would be inevitable tension over the country's vital oil supplies.
That suggests that any partition would simply delay the conflict. But if there is little movement in Tripoli in the days ahead, the Western allies may conclude that it is their best hope of securing a reasonable outcome. They would hope a temporary partition would allow rebels time to regroup and mount another campaign.