Even though polls give Obama an apparent impregnable lead, nobody in the Obama camp is claiming victory yet. McCain can still give us an apparently unexpected surprise.

World opinion unconditionally backs the candidacy of Senator Obama. A recent “poll” in The Economist reveals that 80% to 95% of a “World Electoral Collage” of its readers backs Obama. Gallup published another more scientific poll, which shows that world opinion prefers Obama over McCain by a 3 to 1 margin.

This worldwide support reflects near universal rejection of the Bush Presidency and its party, desire for a change in US leadership, and for a break with all that is associated with Bush and his neo-con circle. The world wants change in the USA and accepts Obama, perhaps in part because the pigment of his skin helps to reinforce the impression that his election will constitute a break with the Bush Administration and what it represents.

However, this near universal support for Obama is not reproduced in the USA. Fifteen days before Election Day, all published polls give Obama a majority, but nothing remotely comparable with the margins outside of the borders of the United States.

In the midst of the greatest economic crisis since the 1929 Great Depression; with the Bush Administration forced to nationalize banks and insurers; the NY stock exchange losing 50% of its value in less than a month; with the country stuck in two wars impossible to exit from; with the international reputation of the nation at records lows; with Obama raising and spending in excess of US$600 million (US$150 million in September alone); what is surprising is that the margin is only 10%.

Obama has never surpassed 52% of voting intentions, and his message has not managed to convert the Pharisees who live between the believers in the East and West Coasts, and which he desperately needs in key states. The greatest economic crisis in living history has barely affected voting intentions.

Republicans tend to improve at the last minute, and in general, more people vote for them that are prepared to admit to pollsters. In 2000, 2% of the electorate voted for Bush more than exit polls revealed, a bit more that the percentage that he improved between mid October and the day of the election. In 1996 Clinton lost 5% in the last 15 days of the campaign, and 3% on Election Day, a similar result to that in 1992 when he lost 4% between October and November 4, and 6% on Election Day.

In 1980, Reagan improved from 40% midway through October to 51% on Election Day, in a three-way race with Carter and Anderson. Ford increased his vote in 1976 from 41% to 49 in the last fortnight. During the same period in 1956, Eisenhower improved from 51% to 58%, as he also did in 1952, increasing from 48% to 55%.

Senator McCain has not lost the race yet.

The Gallup polls most widely cited, those of “registered voters”, disclose that mid-October Obama was the favourite by 52% against 41% for McCain. However, only about 60% of those registered to vote actually do so. When those who do not have a track record of voting are eliminated, Obama’s support decreases to 50% whilst McCain increases to 45%.

Other factors may favour McCain. The Republican candidate is preferred by a substantial majority of “white voters”, among whom only those with post-graduate tertiary qualifications prefer Obama; whilst McCain is preferred by 48% versus 44% among “university graduates”, by those with “some university” (52% v 41%); and by electors with only secondary education (48% v 42%).

The pigment of his skin can cost Obama dearly. Let us not forget that the Democrats have not won a majority of the “white vote” since 1964, when Texan LBJ won the election with 61% of the popular vote. Clinton never won a majority of the white vote. In 2000 Gore fell 12% behind Bush in this key sector of the electorate, and four years ago, Kerry fell further behind, 17% below Bush.

Among non-Hispanic whites, McCain is preferred by a 48% to 44% margin, while the black vote is overwhelmingly pro-Obama (91% against 3%), and Hispanics (60% against 31% for McCain). Likewise, among a highly religious electorate, with more than 60% attending church regularly, McCain is the clear favourite with 64% support among weekly churchgoers, only 28% of which intend to vote for Obama.

The Obama camp is dedicating massive efforts to increasing the number of registered voters more likely to vote for Obama, Blacks, Hispanics and younger voters, and to ensure that they vote. Obama needs to succeed in this strategy to win a victory wished for throughout the world, but in doubt in the USA.

It is also doubtful whether Obama can counter-balance the so-called “Bradley effect”, the famous tendency of part of the electorate to tell pollsters they will vote for an Afro-American candidate, but who do not do so on election day. In 1988, Bradley, a candidate for Governor of California and substantially ahead in all the polls, lost a full 7% of the vote and the election, an effect that has been regularly reproduced in many instances when Afro-American candidates face white opponents.

Although there are differences of opinion as to whether Bradley remains relevant, Charles Henry, the social scientist of the University of California who identified it, believes that although somewhat diminished since 1988, it has not disappeared and could cost Obama 6% of the vote.

We wait to see what role will be played by remaining resentment in key States such as Pennsylvania, where Hillary Clinton was preferred over Obama, and how its combination with cultural prejudices, and local considerations may result in the electorate granting majorities to the Democrats in the Congress but balancing these with a Republican White House, or whether the recent endorsement of Obama by Powell does not became a liability. On its own, Bradley could reduce Obama’s potential vote from 50% to 44%, and simultaneously increase McCain’s from 45% to 51%, a landslide to the Republicans.

We have 12 days remaining to Election Day, the most decisive fortnight, and no matter how much the rest of the world may be surprised; the election result is by no means determined. A McCain victory cannot be discarded until the only poll that counts that of 4 November.