A butterfly's wing beat from the White House
Remember that butterfly whose wing-beat in the Amazon causes a storm over the Atlantic? I think she is hovering over the election right now.
I don't exactly mean the final days of campaigning are straight out of chaos theory. More that it is impossible to predict what small event might matter massively.
Today's employment figures could be one such beat of the wing. They show a very small increase in unemployment to 7.9% - so small the US labour bureau say they are "essentially unchanged".
But the Romney team is bound to seize on this as evidence the economy is heading in the wrong direction and America is not growing.
The opinion polls are still tight, although seven polls in the critical swing state of Ohio have given Obama a lead. Polls from other swing states look good for him, too. The national ones have also seen Obama gaining in the last couple of days.
This might be a reaction to his handling of the storm - a big and important event which also had the effect of keeping the president in the headlines, while sidelining Mitt Romney.
But how much impact will today's employment figures have? Sure, they will be pored over by pundits and endlessly discussed on cable TV, but they may make little impact on voters.
It is clear that the endorsement of Mayor Bloomberg (an independent) and Colin Powell (a Republican), and the thanks given by Chris Christie (also a Republican) for the Democratic president's role in the storm could play powerfully with independent voters. It is not clear whether they will change a single vote.
The candidates think their final rallies matter, otherwise they wouldn't attempt such ridiculous schedules - Obama will be in five different states on Sunday alone. They obviously enthuse supporters, at least those who are there.
But I wonder how much they matter to swing state voters who already feel swamped by unwanted attention from the candidates. Perhaps it is more that we in the media would have a field day if they sat at home doing nothing as the final countdown clock is ticking.
Perhaps the die is cast, but any slip, any glimmer of weakness, any setback may have consequences when both candidates are but a butterfly's wing beat from the White House.