Slate’s Saddamometer giving a US estimate of the likelihood of war has been drifting downwards for a few days, but remains at 68 per cent, near its all-time high.

Meanwhile, numerous British sources have carried reports quoting “a senior cabinet minister” saying that the odds had shifted to 60-40 against action, compared to 60-40 in favour before Christmas. Downing Street (that is, Blair’s office) has dismissed the reports, but they point up the difficulties Blair is facing.

Downing St is quoted as saying “nothing has changed” but, quite obviously, something has changed. Hundreds of inspections have been undertaken and nothing has been found. Despite some recent grumpiness, the Iraqis have opened all the Presidential palaces that were the sticking point last time and have supplied lists of scientists as demanded. The US has, it is reported, started giving its intelligence reports to the UN inspectors, but it doesn’t seem to have been of any use. None of this is conclusive proof that Iraq has no weapons. At the very least, though, it proves that the dossiers on which Blair relied so conspicuously, were worthless.

The next big event comes with Blix’s reports to the UN Security Council, Barring some unexpected shocks, they will say that nothing has been discovered, that the Iraqis have complied with the inspection regime but that the declaration made on December 7 remains inadequate. He may well make an explicit request for more time to continue inspections. The assumption in Washington is that the persistence of the December 7 ‘material breach’ will be enough for war.

But it seems increasingly unlikely that the UNSC will agree. This poses a nasty problem for Blair. He wouldn’t be too worried if a UNSC resolution authorising armed force were vetoed by France or Russia. But it will be very hard for him to sell a war carried out without at least majority support in the UNSC and in a situation where the only obvious case for immediate action is based on American war planning.

Without either Britain or the UNSC, any plan for war would be in massive disarray. A British pullout would almost certainly create a massive attack of nerves in Kuwait and Qatar. Neither government has yet agreed to the use of its bases for an invasion, although it’s pretty clear they would go along with a UNSC-backed war.

Of course, there are still some possible surprises. UNMOVIC could discover a cache of nerve gas or, equally damning, a locked gate with an armed guard. On the other hand, Saddam could upset Bush’s applecart by supplying some documents proving that (some) weapons had been destroyed. Neither seems very likely in the next week, but the second looks more likely than the first.