Hillary Clinton glided through no less than five talk-show interviews yesterday with crisp performances that maintained her apparently stately – and centrist – course for the 2008 Democratic presidential nomination.

However, her 18-point lead over rivals belies frantic paddling beneath the surface of her chief campaign adviser and polling guru, Mark Penn. His new book, Microtrends, describes how public opinion is now a sea of multiple crosscurrents that are pushing American voters in several different directions at once.

“There is no One America any more, or Two, or Three or Eight,” he writes. “There are hundreds of Americas, hundreds of new niches made up of people drawn together by common interests.”

His strategy appears to be a counterpoint to the message of Mrs Clinton’s chief rival for the Democratic nomination. Barack Obama roused the 2004 presidential convention with a famous declaration that religious, political, ethnic and class divisions were nothing compared to “the United States of America”.

In an interview with The Times Mr Penn says that Mr Obama was talking about “outdated concepts”. He claims that “old divisions are giving way more and more to divisions of lifestyle and choice” where people “aggregate themselves into smaller and smaller niches in society”.

Among the 75 microtrends that Mr Penn has identified in his book are “aspiring snipers”, the 1 per cent of Californians aged 16 to 22 telling a pollster - unprompted – that they expect to be a “sniper-sharpshooter” in ten years’ time.

Such statistics are meat and drink to masters of detail like Mr Penn or Karl Rove, the political strategist behind President Bush’s election victories in 2000 and 2004. Mr Rove perfected the technique of “microtargeting” small groups of voters, such as ethnic minorities, with conservative social views on issues such as gay marriage, to build a right-wing coalition.

Mr Penn, however, believes firmly in winning from the centre. “Rove’s analysis was backward-looking and the results of it have been negative,” he says, suggesting that the growth of small disparate groups is “breaking down traditional barriers”, pushing America away from political extremes towards greater tolerance of different lifestyles.

He predicts that this means that “the Republicans cannot run the same campaign as in 2004”, but also accepts that “mass collective action becomes more difficult to organise and sustain” in an individualised world.

Asked about the implications for the left-of-centre agenda for collectively tackling climate change or world poverty, Mr Penn insists that “smaller groups may accomplish more”.

How about sustaining organisations such as political parties? He suggests that in Britain parties are already breaking down, along with old class divisions. Labour, for whom he worked under Tony Blair but “not as yet” Gordon Brown, would be wise to stick with “choice-driven” rather than “state-driven” policies.

Mr Penn points out that the difference between Mrs Clinton’s new policy on universal healthcare, unveiled last week, and the more “monolithic” programme that failed during her husband’s presidency 13 years ago, is the emphasis placed on “personal choice”.

Indeed, in her television appearances yesterday Mrs Clinton repeatedly put emphasis on building a consensus on health and other issues, saying that she wanted to move “beyond partisanship” in politics. While repeating her pledge to bring troops home from Iraq, she was careful to avoid endorsing recent left-wing attacks on military commanders or promising to complete a withdrawal within her first presidential term of office.

As the front-runner for the Democratic nomination, she is bracing herself for fresh efforts by both Democrats and Republican candidates to reinforce the 40 per cent-plus of American voters who still see her as a shrill, polarising figure in US politics.

Mr Penn’s book has a graph showing that all American Christian denominations that ban women clergy have watched their congregations grow, while those that allow it have declined. He even quotes St Paul’s dictum that “I permit no woman to teach or have authority over men”. So what chance has a prospective woman commander-in-chief? “Oh, that’s very different to what has gone on in politics,” her pollster says. “Women make up 54 per cent of the voters, which is a very strong base for a candidate.”

Mr Penn thinks that America is ready for the “first woman in the White House” and the “first female Billy Graham”.

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