Last week it was the turn of the Idaho senator Larry Craig, who in June was caught propositioning an undercover officer in the toilets of Minneapolis airport. Two months later he pleaded guilty to disorderly conduct without consulting his lawyer. Then Craig, who finally resigned over the weekend, claimed that he framed himself. "I was trying to handle this matter myself quickly and expeditiously," he explained. "In hindsight, I should not have pled guilty." If he's telling the truth now he's a perjurer; if he was telling the truth then, he's a gay man who legislates against gay people.

There are moments when things really are the way they seem and facts really do speak for themselves. Bad as the facts may appear, attempting to rationalise them only makes matters worse. Trying to convince people otherwise only insults their intelligence.

So it would have seemed last Tuesday when the US census bureau revealed its latest findings on income, poverty and health. The report showed that since George Bush came to power the poverty rate had risen by 9%, the number of people without health insurance had risen by 12%, and real median household income had remained stagnant. On the second anniversary of Hurricane Katrina we learned the racial disparity in income and the gap between rich and poor show no sign of abating.

Bush declared himself "pleased" with the results, even if the uninsured presented "a challenge". He pointed out that over the past year poverty had declined (albeit by a fraction, and from the previous high he had presided over) and median household income had increased (albeit by a fraction and primarily because more people were working longer hours). Maybe he thought Americans would not realise that five years into a "recovery" their wages were stagnant, their homes were being repossessed at a rate not seen since the Depression, and their pension funds were on a roller coaster.

Having beckoned ordinary Americans with the lure of cheap credit and stock market gains, the invisible hand of the market has now grabbed them by the scruff of the neck and is shaking them mercilessly.

Iraq has, quite rightly, dominated the national conversation and will dominate Bush's legacy. But that doesn't mean it will necessarily be the chief concern for voters choosing their next president. In this week that officially kicks off the presidential primary season, sexual scandal is not the only issue to remind us of the Clinton era. In 1991 Clinton's chief strategist pinned a note on the wall of his campaign headquarters to remind the team of its core message: "the economy, stupid".

A similar focus may once again be necessary, although translating that maxim into votes is not straightforward. Paradoxically, the states with the highest levels of poverty and lowest incomes are staunchly Republican. Poor people tend not to vote, and candidates tend neither to appeal nor refer to them. However, economically they are a glaring and shameful fact of American life; socially and culturally they dominate the centre of almost every moral panic - but politically they do not exist.

None the less, in recent years the conditions associated with poverty have spread far beyond the poor. Almost two-thirds of those who lost their health insurance last year earn $75,000 or more. Homeowners are also not so easy to write off, not least because those hardest hit happen to be in politically sensitive areas. Of the 10 states that have suffered the most from foreclosures, six - Nevada, Colorado, Arizona, Florida, Ohio and Michigan - are swing states.

Among the viable Democratic contenders, John Edwards has embraced the economic agenda most forcefully. In his stump speech he calls for reversing Bush's tax cuts for those earning more than $200,000 a year, cutting poverty by a third in 10 years and eliminating it altogether in 30. Having announced his candidacy from New Orleans he has walked many a picket line in recent months and tells crowds: "The organised labour movement is the greatest anti-poverty movement in American history." With the brooding resentment at growing insecurity now reaching a critical point, Obama and Hillary are also shifting their focus.

Sadly it is unlikely this resentment will gain much in the way of political expression beyond populist rhetoric. The notions of personal reinvention and economic meritocracy that lie at the heart of the American dream are far more powerful and enduring than the kind of class consciousness necessary to redress the imbalance between rich and poor. Inequality of wealth in the US has long been justified on the grounds that there is equality of opportunity. The trouble is that while inequalities have grown dramatically over the past 20 years, equality of opportunity has been all but eroded.

According to the Economic Policy Institute, in 1989 American CEOs earned 71 times more than the average worker - today, by most calculations, it is up to around 270 times. Meanwhile, social mobility has slowed to a level below that in most of Europe, including Britain.

Most Americans identify themselves as "middle class" - but in the middle of what is not clear. Anything that would identify working people as a group with a collective set of interests that are different from and at times antagonistic to the interests of corporations has pretty much been erased from public discourse. People will refer to "blue collar workers", "working families", "the poor", the "working poor". But the working class simply does not exist.

None the less, class does play a role. It is most often used by the right to cast liberals as cultural "elites". The price of Edwards's haircut, John Kerry's windsurfing, Al Gore's earth tones - all are exploited as illustrations of the effete mannerisms of those who claim to speak for the common man and woman. Class is not elevated to politics but reduced to performance: that is how the fact that Bush has made so little of his elite upbringing has become an asset.

The conservative columnist Cal Thomas said of Edwards: "His populist jargon is nothing but class warfare." If only. Long ago the wealthy declared war on the poor in this country. The poor have yet to fight back.

In October 2000, Bush quipped to a group of wealthy diners: "What an impressive crowd: the haves, and the have-mores. Some people call you the elite; I call you my base." If only the have-nots had such a determined and confident advocate.

g.younge@theguardian.com