Nobody knows what will happen on Tuesday, but there is a clear chance that one of the unlikeliest events in American political history could take place. A miscegenated black man could become president of the United States. And if the polls are accurate, the state of Virginia will be critical in any Democratic victory.

This state has not voted for a Democrat since 1964 but now gives Barack Obama a lead of about six points. That is remarkable from the perspective of the past few decades – but much more staggering when you take a longer view.

Virginia contains Richmond, once the capital of the Confederate slave states. As recently as 1961, when Obama was born, Virginia would have ruled his parents’ marriage illegal, because it was inter-racial. In fact, it was not until Obama was six that Obama’s parents’ marriage would have been made legal in that state, and Obama ceased being illegitimate. And that happened only because the US Supreme Court forced it. That is how far Virginia and America have come in Obama’s lifetime – and ours.

It would be easy to rhapsodise too sentimentally about this – but just as easy to understate its momentousness. I do not believe Americans or anyone else in the world will fully absorb it until it happens.

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America, after all, was founded on one principle, freedom, but permeated by another, slavery. Slavery was America’s original sin and Obama is the fruit of its slow and painful self-absolution. The civil war over the question was immensely bloody – far bloodier per capita than any other war in American history.

The victory of the north led to intense resistance in the defeated south for a century of segregation and cruelty – and still divides the country to this day.

In fact if you place a map of the states that favoured the proslavery south over a map of the states that are now showing a trend for John McCain, you will get an almost perfect match. The only differences: Virginia has switched sides, and West Virginia has too. (It is now for McCain.) Florida, once part of the Confederacy, is also now prone to vote Democrat because of a massive influx from the north.

The rest is essentially unchanged since the 1860s. Even in America, the past controls the present.

Obama – for extra historic piquancy – is from Illinois and began his campaign in Springfield, where Abraham Lincoln started his. Like Lincoln, Obama is trained in the law, came from a humble background, and is aiming for the presidency with almost no executive experience.

People forget how inexperienced Lincoln was when he took office after one of the worst presidencies in American history – James Buchanan’s. Lincoln had held no legislative or executive office and had been a congressman for only two years previously. He became a national star primarily because of his oratory. Sound familiar?

Lincoln’s task is Obama’s: to unite a deeply fractured country. Lincoln’s challenges were far greater, but if Obama wins on Tuesday he will still face an immense set of challenges.

The United States is in two gruelling wars thousands of miles away, neither of which appears to be approaching anything that could be called “victory”.

In a mere eight years President George W Bush has doubled the national debt he inherited and turned a federal surplus into a half-a-trillion deficit.

Bush’s Republicans have also added a cool $32 trillion to future government liabilities and kept taxes unsustainably low unless entitlements are slashed in a manner no politician would contemplate. America’s real economy is in a recession and its financial stability is in doubt. Economic inequality has soared and cultural polarisation has intensified. The crisis America finds itself in is reminiscent of 1980, and perhaps 1932. Whoever inherits Bush’s awful legacy will have his work cut out.

A President Obama would start with the task that bedevilled his two predecessors. America remains deeply riven and the past president exacerbated those divides to keep himself in power.

You can see the fruits of that policy everywhere in the McCain campaign. The hardest core of McCain’s supporters seem not just to oppose Obama but to regard him as inherently illegitimate. They see him as at best a socialist and at worst a traitor. A clear minority refuses to believe he is a Christian and many believe he is not merely Muslim but allied with Islamist terror.

McCain and Sarah Palin, desperate to find an argument to wrest themselves out of their polling deficit, have deliberately and clearly legitimised this line of attack. Palin has said that Obama has been “palling around with terrorists”. A McCain spokesman last week said on cable televi-sion that Obama was a friend of antisemites. The now-famous “Joe the Plumber” has said that an Obama presidency would mean “death to Israel”. The paranoid strain in American politics, long present, has made Obama’s task of uniting the country if he is elected that much harder.

Indeed, there are many signs that if Obama wins, the strategy of the Republican right will be to treat him as potentially treasonous until proven otherwise. Any outreach Obama might make to, say, elements in the Iranian regime will not be interpreted as hardheaded diplomacy, but as proof that Obama is in covert league with America’s enemies. Any withdrawal from Iraq could lead to a “stab-in-the-back” narrative that blames treacherous leftist elites for waving “the white flag of surrender” and betraying good American soldiers.

Many on the far right have advanced themes that suggest that the election is being stolen by Democrats and their allies by fraudulently registering black and Hispanic voters. McCain himself asserted in the final debate that what might be at stake is the biggest voter fraud in the history of American politics – an absurd hyperbole, but one deployed aggressively nonetheless. These are dangerous waters to swim in, but, sadly, the fringes of the far right have come close to defining the Republican party.

If Obama wins big, moreover, he could face bigger challenges than if he wins by a conventional margin. The devastated congressional right will be reduced to those in the safest seats with the most ideological bent. Just like the Tories after 1997, the Republicans could marinate in their own denial before they wake up and move painfully back to the centre.

Already, some are positioning Palin to be the standard-bearer for the next wave of Republicanism – a potent combination of populist antielitism and religious zeal. If you consider how the right responded to Bill Clinton’s election in 1992, and then add race to the mix, the prospect for calm ahead is slight.

Equally, too big a Democratic majority in the House and Senate could make Obama vulnerable to left-liberal hubris and conservative Democrat revolt. Few economists recommend fiscal austerity in the current downturn, but there is a risk of empowered Democratic power brokers on Capitol Hill overcompensating and initiating a binge of favoured spending projects in their own constituencies.

Any spending increase by Obama will be reliably greeted by a chorus of “socialism!” from the opposition (an opposition that said almost nothing while Bush increased federal spending by a bigger margin than any president since FDR) and any tax increases in a recession will prompt overwhelming caterwauling as a further drag on the economy.

My bet is that his tax rises will be more modest than advertised. By the time Clin-ton became president, remember, the recession of the early 1990s was almost over. When Obama becomes president, it will just be beginning.

On climate change, the task will be made much harder by that depression – as Obama’s cap-and-trade scheme would indisputably hurt business. On immigration, Obama would easily be able to pass a bill favoured by Bush, but also face a nasty backlash from the right and maybe even in his own party.

Obama may even be leery of his signature healthcare reform, remembering what happened to the Clintons in 1993. And the price of a big majority will be a lot of Democrats in marginal seats in normally Republican states who may well bolt if Obama gets too liberal.

Managing all of this will not be easy. And Obama will also have to deal with Democrat-run congressional committees finally getting a thorough look at what the Bush administration has been up to in the past eight years.

Among the issues that will be impossible to avoid will be evidence of war crimes and torture authorised by the outgoing president and his closest aides. Prosecu-tion? A truth and reconciliation commission on the South African or Chilean mod-els? All we can say with certainty is that these are difficult questions in which maintaining the political centre will be extremely hard.

Equally, if Obama is too cautious and too careful not to divide the country, he could end up squandering his own mandate. He has potential enemies to the left of him as well as the right. If he is elected, he will cap a generation of rising anger and frustration on the Democratic left. From their point of view, the Clintons were semi-Republicans in the 1990s, the 2000 election was stolen and the 2004 election was an artefact of warmongering and religious pandering. They do not just want to win. They want to get even. They have a head of steam that could scald Obama as powerfully in office as it has helped propel him to the verge of the presidency.

There is also an enormous liability for Obama in the great hopes he has inspired. The reason for the wave of optimism behind him – just look at the massive crowds across the country this past year – is almost entirely due to the profound national demoralisation of the recent past. Iraq and Afghanistan, Katrina and the financial meltdown, torture and religious extremism: all these have led many Americans to the brink of despair about their own country. A historically unprecedented number of Americans believe their country is on the wrong track and view Obama as the vehicle to repair it.

Among the most enthusiastic Obama supporters, there are tinges of hero worship and aspirations beyond anything any human being can deliver. And the hostility born of dashed expectations is always the worst. People expecting a messiah will at some point be forced to realise they have merely elected a president.

No president will be able to wave the wars in Iraq and Afghanistan away with some kind of magic wand – there are few good options in either conflict, and many potential perils. No president will be able to end a recession with deep roots or alter market confidence in a single speech.

No president can change the Earth’s climate in four or eight years. And when Obama’s limitations emerge, as they will, there is a danger that the powerful expectations of his young base may turn to tears. This is always the risk with political “movements”. They conjure up utopias that can simply never happen.

Between the roiling and increasingly bitter rapids on the right and the left, can Obama maintain a steady course? We cannot know, of course. But the evidence of the past year is encouraging. What has been truly amazing is the preternatural calm and moderation Obama has shown throughout this volatile and emotional campaign. He has managed to get to the brink of the White House by beating some of the most formidable political machines in America – the Clintons and the Roves – without intensifying the conflict or polarising the country himself.

He seems able to absorb these currents without further disturbing them. Of course, this is much harder in office than in opposition. In office, you have to make decisions that delineate winners and losers rather than make speeches onto which everyone can project their interests. But Obama seems unafraid of his enemies, undeterred by his rivals, and able somehow to stay healthy and cheerful.

His temperamental edge is complemented by his organisational and managerial skills. The most seasoned political observers have been struck by the meticulous professionalism of his campaign; and there has never been a fundraising machine as innovative or as successful as his in the history of American politics.

Moreover, he has put himself out there in the most Republican of Republican states. He looks competitive not only in usually Republican Virginia, but also Ohio, Colorado, Montana, New Mexico, Indiana and even Georgia. In one of the more surre-al moments of last week, it looked as if the Obama campaign was considering a serious last-minute effort in Arizona, McCain’s home state.

My own view is that Obama is a midwest-ern centrist in his gut. He is much more like the Clintons substantively than either he or the Clintons would care to admit. The right’s biggest mistake in this campaign has been to believe that Obama is a closet radical and that if they could expose that, they would win. Although Obama is a product of his generation and of academia, his proximity to the intellectual left does not seem to have affected his policies.

His healthcare plan is less leftist than the Republican Mitt Romney’s in Massachu-setts. His proposals cut taxes for 90% of Americans. His climate change proposals are tediously conventional (too conventional to my mind). His instincts on foreign policy are more George H W Bush than George W Bush, which is to say he’s a pragmatic empiricist. If I were to bet on one appointment that Obama will make to his cabinet, it would be keeping Robert Gates, the defence secretary, at the Pentagon.

He is a strange liberal who seems to get along famously with conservatives. And he has now run up quite a roster of conservative endorsements, from Colin Powell to Francis Fukuyama. This is partly why a historical perspective on Obama does indeed return to the figure of Lincoln and the trau-ma of the 1860s.

In the middle of an unbridgeable divide, Lincoln kept calm. He inherited a much more divided country, of course. Lincoln did not even campaign in most of the southern states – he was not even on the ballot in most of them. By the time he was elected, many of them had already seceded. But Lincoln’s dedication to the cause of abolishing slavery was matched by a moderate demeanour and an extreme aversion to political polarisation.

Lincoln famously staffed his cabinet with what the historian Doris Kearns Good-win has called a “team of rivals”. Think of the way in which Obama handled the Clintons. He gave them just enough rope to hang themselves but managed to avoid a real breach. Last week Obama was jointly campaigning with Bill and comparing his economic proposals to Clinton’s in 1992.

That is a unifying skill Lincoln had and Obama will need. Obama’s capacity to pacify his enemies and organise his friends is his most telling characteristic. It should not be mistaken for softness. There is steel behind the velvet. But the velvet is really smooth and comfy.

Obama will also have something Lincoln never had. He will be in his DNA the visible incarnation of a wound that dates to America’s beginnings. If he is elected president, there will be a healing of some sort deep in the country’s psyche. That act will be a catalyst for unknowable change in America and in America’s role in the world. We can and should focus on his challenges, on the divisions still festering in America, on economic crisis and military quagmires. But what Obama appeals to is what Reagan appealed to: an American optimism that problems can be solved and divisions can be overcome.

In the coming week, if he is elected, we would be wise to resist euphoria or sentiment. But we would be wilfully blind not to sense the gravity and potential of the moment as well. We could have the first black president, with a congressional majority of a size not seen since Lyndon Johnson. We could see a landslide among the young. We could see an unprecedented African-American turnout – a moment when black Americans actively take ownership for the first time of the society in which they have always been such an integral part.

We simply do not know what new realities this moment could unleash. What we do know is that this is history – epic, deep, momentous history.

Let us keep our heads. But let us not numb our hearts. Somewhere in a Burkean idyll, countless Americans who lived before us, the souls of so many black folk and white folk across the centuries, are watching. What would Washington have said? How could Lincoln believe it? How amazed would Martin Luther King be?

We are indeed on the verge of something that seems even more incredible the closer it gets, something more than a mere election. This is America, after all. It is a place that has seen great cruelty and hardship in its time. But it is also a place that yearns to believe naively in mornings rather than evenings, that cherishes dawns over dusks, that is not embarrassed by its own sense of destiny. In this unlikely mixed-race figure of Barack Obama, we will for a brief moment perhaps see a nation reimagined and a world of possibilities open up. For a brief moment at least.

As they have learnt to say in some of the most blighted parts of the world at some of the most desperate times: know hope.

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