Dubya was probably always going to be the only person who could unite the Democrats. Speaking to the Knesset, he compared anyone who would talk to ‘our enemies’ as the equivalent of Neville Chamberlain in 1938. Poor old Neville. Practically everyone supported his actions in letting Hitler go into Czechoslovakia that year – no one was actually in favour of a pre-emptive invasion of Germany, not even St Winston. But Chamberlain was the bloke holding the flapping piece of paper. So he got it.

Indeed, if anything comes close to the spirit of appeasement, it’s the manner in which money and guns have been handed over to Sunni gangs in Iraq, to fight Al-Qaeda groups – a pretty effective way of making the establishment of civil society impossible in the future.

But of course the none-so-subtle target was Obama, and the radical idea that a nation should talk to countries it has differences with, for its own and general interests.

The tactic would seem to have backfired, as does everything Dubya does these days, short of being seen hugging a giant rabbit. Within hours of the statement, the Republicans and their media wing, or FOX news as it is known, were already on the defensive, not ramming home the idea that Barack Hussein Obama was a useful idiot, but that Bush’s comments were a “reasonable thing to say” – pretty much standard damage control, translating the issue to a higher, more abstract level, making the debate about the debate.

They wouldn’t be doing that if they weren’t convinced that Bush was poison to the cause – and indeed McCain has gone out of his way to establish some distance between himself and that style of campaigning – even his remark that Obama was the preferred candidate of Hamas was something he seems to have regretted and tried to qualify.

For the thing is that of all the many things that worry people about Obama, his suggestion that the US should talk to its enemies doesn’t seem to be one of them, per se. Those who do think that he’s not presidential material do so out of an assessment of his whole character, not of his particular policies. Even conservatives don’t subscribe to the neocon version of America as a crusader in the world, projecting virtue.

Indeed, Bush’s Knesset speech is a rich vein of cultural interpretation. Bush quoted a Senator who had said in 1939 that “if only he could have talked to Hitler, he wouldn’t have invaded Poland”. The senator in question was a Republican, a champion of the powerful isolationist strand of US political thinking, which kept the US out of WW2 in Europe until Hitler declared war on them, forcing their hand.

Right up to Vietnam, the right was always isolationist (apart from dirty little wars in South America), and the current neocon enthusiasm for foreign crusades was a product of a movement that had begun as Trotskyist internationalism in the 1930s and gradually moved rightwards.

If right wing Americans can still be drawn on to support the war, it is not out of any crusade – it is out of questions of honour, or finishing the job, or duty to the fallen. It’s loopy, but internally consistent, and it’s an utterly different ethos to the WW2 Mark 2 Bush is selling. Indeed, McCain has already sniffed the wind and mentioned 2013 as a pullout date, an essential concession that his “100 years” remark has been a disaster and will come to haunt him in the campaign ahead.

Point is McCain can get away with a lot in Iraq as an old soldier – Dubya can’t get away with nuttin’ being a sleazy AWOL draft dodger. But nor is he executing any complex strategy. I mean the man’s just an obvious moron. He was filled with a story by the neocons and he’s stuck to it, because without it, he wouldn’t exist – he’d just be an amiable guy hanging round a ranch at Crawford.

So he doesn’t really understand how deep an isolationist streak runs in American life, beneath the crusading palaver – the desire to just go back to the farm. True, it’s at war with American exceptionalism, the idea of bringing the revolution to the world, but that narrative tends to work only when the going is easy – when you get drawn into the arguments of jabbering foreigners, people start to think about going back to the farm. George Washington was wont to sign himself ‘Cincinnatus’ in memory of the Roman general who saved the city and then returned to his farm, and there’s nothing like intractable wars to bring out that streak in American life.

Hence, and this is the unity thang, Hillary jumped in to defend Obama on the count of appeasement. Party loyalty? A sense she’d gone too far with the ‘hardworking white people’ remark? Who knows? Obama for his part swung it right round onto McCain, barely mentioning Bush in his reply at all – exactly the sort of thing McCain doesn’t want to happen.

The way that Bush’s remark has been received is a slight but crucial mark that the whole election may be swinging around to make Obama the presumptive. Yesterday’s Mississippi result has been the fulcrum on which the presumption of Republican f-ckedness is being based. With the Edwards endorsement, it may be the day we remember as the day the Obama road to the White House really began.

But there is a crack in everything (that’s where the light gets in) – today’s ruling by the California supreme court that substitutes for gay marriage are unconstitutional throws the whole issue back into the public domain.

It will revive the whole debate of a junk amendment – in every sense of the term – banning same-sex marriage in the Constitution. Will that issue be the horns of a dilemma on which the Democrats are gored? Again? Or have things become so serious that American politics has finally become so too?

We shall find out…