Were I an American electoral officer (at the risk of sounding like Brideshead in the novel, whose mind was full of such unlikely suppositions), I should be checking the punching mechanism on my Votomatic pretty carefully right now.
All the indications are that the presidential election could be as tight as the contest between George W Bush and Al Gore in 2000 when, as you'll recall, we first learned about "hanging chads", which the Floridian vote-counting machines couldn't handle. As a result, Dubya headed to the White House, while Al was reduced to making a tedious and forgettable film, either about climate change or eating hamburgers for breakfast, lunch and dinner – judging by his dimensions these days, probably the latter.
It would be nice if there were no arguments after this presidential election, but I wouldn't count on it or, rather, I'd be sure to count very accurately. According to the polls, President Obama was yesterday still (just) in front – but by a margin of only 0.2%.
Because each state provides a certain number of electoral votes, and most cast all of them for whoever was the more popular candidate, it is possible that the man elected as president may not have won the popular vote. Indeed, that was the case 12 years ago, when – even leaving aside the debacle in Florida and the fact one elector in DC abstained – Mr Gore got almost half a million more votes than Mr Bush, but only 266 electoral votes to the president's 271 (270 is the magic number).
This time, there are simply too many states which could go either way – including Florida, Michigan, North Carolina, Ohio and Pennsylvania, which all have 15 or more electoral votes – to make any prediction.
Since almost all the commentators agree that the economy will be the determining factor, it might seem odd that things are so tight. In fact, however, that may be one of the reasons why the race is close. America is still in the middle of a stuttering recovery – last week's economic figures weren't bad enough for Mitt Romney to land a killer late blow, but nor were they unalloyed good news. Unemployment went up, and seems to be stuck around the 8% mark, far too high for comfort or growth.
Even after an economic downturn, there is often furious dispute about whether the measures taken worked or not (for example, the figures suggest the New Deal did nothing to reduce unemployment during the Great Depression, though Keynesian economists believe the opposite). While still in the throes of the crisis, as America is now, it is easy to depict your opponent – any opponent – as recklessly incompetent or ideological, but much harder to present an obvious solution.
This accounts for the fact that, though the rhetoric suggests a yawning chasm between their positions, President Obama's and Mr Romney's economic policies are not as different as all that. In part, that is because the president has been prevented from pursuing the policies he wanted, not least by the election of a sizeable number of fiscal hawks in 2010 who dragged deficit reduction to the centre of the debate. Partly as a consequence of the Tea Party tendency, and partly because Mr Obama insisted on pushing through healthcare reforms in the face of strong opposition (alienating some who were potential allies on other issues), there is currently no chance of agreement on the budget.
Opposition of this sort actually helped Bill Clinton's presidency. With the benefit of hindsight, history will probably judge his time in office more favourably precisely because the "Contract with America" Republicans prevented him from doing many of the things he would have liked to. But for Mr Obama, it means he is currently having to defend an economic policy he didn't devise.
On the face of it, Mr Romney's economic policy is bound to be better, if only because he's likely to introduce bigger cuts. Yet we can't be sure, because he has been amazingly vague on the details, though he implies approval of the budget advocated by his running mate, Paul Ryan. And although Romney took the easy option of loudly damning "Obamacare" – the unpopularity of which it is difficult to overstate, baffling though British voters may find it – he introduced an almost identical system when he was governor of Massachusetts.
The upturn in Mr Romney's fortunes dates from his appointment of Mr Ryan as vice-presidential candidate, and they were boosted by the first presidential debate – not just because he was thought to have won it, but because he was so much better than the portrait the media had painted of him until that point.
By contrast, the president (inevitably, just because voters grow disenchanted with those in office) now has little of the sheen, promise and potential for transformation which surrounded him four years ago.
On social issues, Mr Obama is always going to be the liberals' preferred choice, a point he's pushed with his position on gay marriage and by characterising conservative views on abortion as "war on women". But he has been far less liberal than might have been expected, as his slowness to act over Guantanamo and his enthusiasm for extra-judicial assassination of suspected terrorists both testify.
In any case, although you'd be unlikely to discover it from the British or indeed much of the American media, most Americans are not liberals. And there is one other factor which should be borne in mind: Mr Obama can't deliver the first term in office for an African-American again.
The goodwill which got him into office, because he looked inspirational, capable of transforming the country and – because it matters – because he is black, may no longer be there. Inspiration has been set aside for dull – to be honest, uninspired – management, hope replaced by pragmatism and lofty ideals by drone assassinations. Above all, the economy remains untransformed. To put it unfairly, voters who supported him to reassure themselves that they weren't racists don't need to do it again, and he isn't offering much else. But will they like Mitt any better?