With air drained from the last balloons at the party conventions, the contenders - President Barack Obama and Republican Mitt Romney - are sprinting into the last days of the presidential campaign locked in a very tight race.

With over 20 million people in need of fulltime work, the overriding issue, not surprisingly, is the economy.

MostAmericans think the country is on the wrong track.

Most disapprove of the way that Obama has handled the economy. Romney wants this election to be a referendum on the president’s record.

His strongest case is simple: “the economy is wretched; Obama has failed; we need a change.”

Most of the academic models that predict election results based on economic data project a Romney victory.

But Romney is a hapless candidate, a shape shifter who has changed his colors on a broad range of basic issues to fit the election environment.

And he is running on a platform that tries to sell once more the very policies that helped drive the economy over the cliff – top end tax cuts paid for by savage cuts in basic social supports, more military spending and adventure, and financial and corporate deregulation.

So Obama benefits big-time if voters see the election as a choice of direction.

Former President Bill Clinton distilled it best in his tour de force at the convention:

“We think "we’re all in this together" is a better philosophy than "you’re on your own,” warning against Romney who wanted to “double down on trickle down.”

(Trickle down economics – giving tax cuts to the rich in the hope something will trickle down to workers – was first popularized by Ronald Reagan).

The two parties also increasingly represent two different Americans.

Republicans, as displayed in Tampa, are increasingly a “pale, male and stale” minority party – older, virtually all white, disproportionately male, and of course more affluent.

The Obama Democratic coalition is younger, diverse, disproportionately female, and contains both more low income voters and more voters with post-graduate degrees.

With few voters undecided, the outcome is increasingly a question of turnout: which candidate will do the better job of turning out his base to vote in a handful of key swing states.

On this, polls aren’t helpful, and pundits know little.

Democratic activists are mobilized by the threat posed by the Romney agenda and the right, but key pro-Obama constituencies – the young, single women, minorities – have been the hardest hit by the economy.

Right-wing activists are afire at the chance to “send Obama back to Chicago,” but Romney is neither respected nor loved by the conservative voters.

Seniors, a key Republican constituency, tend to vote in higher percentages than the rest of the population, but are increasingly worried about Republican plans for Medicare, the senior’s vital health insurance program.

Non-college educated white blue collar workers have been voting Republican in ever larger numbers, but are likely to think twice about electing a “vulture capitalist” from Wall Street.

Also unprecedented is the big money – much of it anonymous – flooding into both the campaigns and the so called “independent” operations.

A projected $3 billion will be spent on the election, the overwhelming proportion on negative ads plastering television sets 24/7 in a handful of swing states.

American elections have been increasingly expensive and increasingly negative, but we’ve never witnessed this kind of excess.

Negative ads tend to depress turnout, which make them attractive to a minority party candidate like Romney and to a president running for re-election in a foul economy.

On top of this is an unprecedented effort by Republican governors in key states like Ohio, Pennsylvania and Florida to fix the game, passing “election reforms” – requiring official ID, limiting periods of voting, limiting access to voting stations – that are clearly designed to make it harder for the young, the poor and urban minorities to vote.

In sum, the US is headed into a fiercely competitive campaign that will be bitterly contested over the next two months and for months after the election is decided.

Whatever the outcome, this election will leave America more divided and the parties more polarized than ever.