Tomorrow will see a major demonstration against the war in Washington, which will be crucial for three reasons.

First, it will be a significant test of the level of disquiet about the war. The extent of anti-war feeling has been known for some time. But this will give some indication of how much people care. From the response to Bush's state of the union speech earlier this week, which ranged from at best tepid to at worst contemptuous, it is clear he is isolated. What's not clear is if that is going to make any difference on the ground.

That will depend on the Democrats, bringing us on to the second reason why the demonstration is important. The Democrats have only moved as far as they have on the war in the last few weeks because they have been pushed by campaigners. And that is still not far enough. True, they are working within relatively narrow constitutional parameters since, as commander-in-chief, Bush controls foreign policy and the military. But so far, their reliance on symbolic opposition is really little more than a slap on the wrist. A year ago, when Republicans ran Congress, this would have been a considerable achievement. But given that his isolation is now an accepted fact of political life, all a symbolic vote does at this stage is expose their impotence.

Finally, it will be interesting to see if any of the Democratic presidential hopefuls show up. The chance of that happening stands at around zero - with the possible exception of Kucinich. But for purely cynical political reasons, I think they should. Just as Kerry believed he couldn't get elected without voting for the war - which was a mistake - so these cautious democrats will have to ride anti-war opinion in order to win their nomination. It's too early to tell what state the war will be in, in a year's time, but one wouldn't need to be a genius to know it will be a mess, the American public will be even more desperate for someone who will get them out of it and a candidate who looks like they took a stand early and publicly will be well positioned.