America’s big four television networks aired a party political broadcast lasting 30 minutes on Wednesday at peak viewing time. This being the land of the free but no free lunch, the “informational” on Barack Obama was paid out of his war chest, the biggest in American history. No British-style equal time for John McCain, though many Americans could and probably did switch channels. Still, for a few minutes at least, millions caught it.

The broadcast bore the hallmarks of David Axelrod, the artful operator who has made a career out of marketing black candidates to white voters. In his tried and tested winning formula, Obama was sold as the opposite of “the angry black man” of white racist nightmares. He was cool, reassuring and reasonable.

On screen, Obama’s candidacy was endorsed by Eric Schmidt, chief executive of the hippest company on the planet, Google, while white military men lined up to give him the salute. The support of white role models is an important part of the Axelrod strategy. So is telling the voters that backing the black candidate puts them on the right, or rather the righteous, side of history.

Like the best advertising, some of the message rings true. Though it was too long, those who persevered to the end could not doubt that Obama is a class act: a first-rate Harvard intellect with a first-rate temperament. Franklin Roosevelt was accorded only the latter accolade.

As Axelrod’s colleague David Plouffe pulls in armies of volunteers and millions in contributions through the internet - I am getting up to four Obamamails a day and I don’t even live there - old professionals are slack-jawed at the most phenomenal campaign in US history.

Carl Wagner, Ted Kennedy’s campaign manager who also helped Clinton win his first victory in 1992, is gasping. “Last year if you had told me Obama was going to raise $700m and get 3m new donors I would have been inclined to call a mental hospital,” he says, aghast at the size of the Democratic candidate’s rallies in the heart of the old Confederate South.

Former senator Wyche Fowler, a veteran of one of the closest contests in postwar American history, can’t believe the size of Obama’s volunteer army in his home state of Georgia: “I’m predicting a landslide on Tuesday.”

But a landslide for what? The inexperienced Obama is a blank page on which half the country has written its hopes. Like new Labour in 1997 he preaches consensus healing. His campaign has succeeded through cautious restraint, his mantra of change allowing him maximum room for manoeuvre. The talk is a Republican titan will head defence or the State Department.

Obama’s ability to “redeem” or heal America has been widely overhyped by the liberal media. Like Tony Blair, will inexperience mean he is similarly slow to learn to use the levers of power? Abroad, he has already been greeted as a hero though he will soon be tested. The weight of expectations is almost too great. If organisation and money are the criteria for success, the Democratic candidate is set to win big. Certainly, large sections of the Republican party believe it. They have already begun their acrimonious “Who lost 2008?” debate. They call to mind those shrill, ugly Tories who lost in 1997 and blamed the electorate.

Brave souls defy conventional wisdom and point to narrowing opinion polls. Their last rallying cry is the Democratic candidate’s alleged socialism. “Spreading the wealth around might become the epitaph for his candidacy,” whistles Dick Morris, a Republican spin doctor. The McCain camp plays up the memory of Truman’s famous surprise victory over Dewey in 1948 to whip up last-minute support.

A month ago McCain had a 20-point lead on Iraq and was giving the Democrat more than a run for his money. And no wonder. His lobbying for a change of strategy led to General Petraeus’s surge, which reduced casualties and kept the country from falling apart. The surge was opposed by Obama. When Russia invaded Georgia in August, McCain sounded the alarm while his opponent was lost for words.

But ever since the financial giant Lehman Brothers crashed, the economy has become the big issue. There was already discontent. Despite America’s increased prosperity, middle incomes have ceased to rise according to received opinion (though many economists dispute it). The past 12 months have seen stagnation. The past two months have been a disaster. The mass in the middle or at the bottom have suffered an asset collapse as their retirement funds and house prices plummet and their jobs are in jeopardy.

Fear really is the key. Globalisation means that for the first time low-skilled American workers will be competing for jobs with low-paid workers in the Third World, putting downward pressure on their wages. The same global forces mean the skills of the West’s managerial and entrepreneurial classes are better rewarded. The rich get richer and, unlike Warren Buffett, the investment sage now advising Obama, not all of them have worked hard to get it.

Obama proposes tax rises on families earning more than $250,000 a year. The effect could soon be felt across the Atlantic. Labour’s left and the Liberal Democrats have long called for higher rates of tax on incomes over £100,000. Now they will no longer feel out of time.

“I think I will know what Obama will do if elected - he will send me a $1,000 cheque unless I am in the top 5% of the country,” says David Frum, a despairing apostle of modernising conservatism. “McCain’s message on the economy is more complicated. First the economy is fine, then it’s crisis, then. . .”

McCain’s campaign has no central argument, laments another disappointed supporter, David Brooks. “His proposals don’t add up to more than the sum of their parts.” He has run a campaign based on biography. That has compelled him to discuss the inadequacy of his opponent’s, but negative campaigning hurts both the target and the person who does it. McCain, the least partisan candidate in years, has allowed himself to be portrayed as a rightwinger chained to religious fundamentalists.

The right’s fear - and the message of their final appeal to the voters - is, in the words of Minnesota’s Governor Tim Pawlenty, that the elections will create a “runaway train”. A Democratic president urged on by a House of Representatives with a bigger Democratic majority and a Democratic Senate with a filibuster-breaking 60 seats could end the conservative era inaugurated by Ronald Reagan 30 years ago and go on to make fundamental changes to the economy.

Speaking about the $700 billion government bailout of the banks, Frum argues: “This concentration of financial and government power is very dangerous. It is better to have it in the hands of a limited government man - a message I haven’t heard from McCain.

“Do you want the government to tell the lending companies how to lend? Do we want to see the government saying to banks we look more favourably upon your application for credit if you lend in the right regions, if you have a bigger minority lending programme or do manufacturing in the United States? These are preferences already inserted into tax law.”

Exaggerated fears or no (and Obama has latterly surrounded himself with experienced economic advisers), the Democrat’s promises to unions and zeal for regulation frighten capitalists. The absence of tough rules has hurt capital-ism but imposing suffocating rules will kill the golden goose.

The momentum of Obama’s vast campaign and the economic crisis in the US will mean many naturally sceptical folk will cheer a likely Obama victory on Tuesday. When Axelrod goes home to Chicago, it will be up to the candidate to prove the campaign wasn’t the message but the beginning of something better.

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