The worst case scenario is that an election that lacks legitimacy for a large number of Iraqis could pitch the country towards civil war and territorial break-up.

But - as astute analysts point out - Iraqi politics are not just a question of the Sunni-Shia rivalry.

Sunni Muslims are far from being a monolithic group that acts in a unified way.

Even the Shia - with their more hierarchical tradition than orthodox Sunnis - display divisions that are not often recognised.

Firstly there is the dichotomy of religious Shia versus secular Shia.

Then there is the Iranian Shia tradition, most prevalent in the holy centres Najaf and Karbala, versus the Arab Shias, rural poor and slum dwellers, many of whom follow the radical cleric and erstwhile insurgency leader Moqtada Sadr.

Shia divisions

The United Iraqi Alliance, list 169 as it's identified on the ballot, with its presumed backing from the Grand Ayatollah Ali Sistani, is the natural home for Shias from the Iranian tradition.

They may in fact not vote at all, seeing no relief from their destitution in this political process or the American occupation that set it up.

Nevertheless, the United Iraqi Alliance is expected to receive the largest share of votes.

Middle-class Shias on the other hand may see interim Prime Minister Iyad Allawi as a saviour from creeping religious influence, as well as from the raging Sunni-led insurgency that has cost thousands of Iraqi lives.

Mr Allawi comes from the same urban, secular roots, although he lived in exile for many years, and has cultivated a tough-guy image that some Shias see as the only way to defeat terrorism. But it has won him many enemies as well.

Mixed messages

The Sunni situation is where these elections become really problematic. For Shias, it is an opportunity to assert their numerical power, with an estimated 60% of the population from the Shia creed.

But for Sunnis (about 20% of Iraqis), it will put the seal on their disinheritance after a long, enriching and turbulent dominance over Iraq.

However, another leading Sunni group, the Iraqi Islamic Party, has put forward a list of candidates - though now it's calling for a boycott because of security concerns.

And the AMS itself says Sunni voters in the northern provinces should vote anyway, to prevent being swamped at the polls by Kurds, who are all too keen to end their own decades-long exclusion from power in Baghdad.

Fear of violence

But there is a secular tradition among Sunni Muslims that is even stronger than Shia secularism.

In fact, some analysts argue that divisions over how great a role religion should play in Iraqi politics are more important than any division between Shias and Sunnis.

The question for them, therefore, is whether it is safe to vote, given that any manifestation of electoral activity is considered a target of the insurgency.

The US and Iraqi authorities are enforcing some of the most draconian security measures ever seen to ensure a free election.

There are also more than six thousand polling centres - an impossibly large target for an insurgency that at its height managed fewer than 150 attacks a day.

That said, you only have to kill a handful people to terrorise an entire population.

Unpredictable results

So will Sunni participation be strong enough to give the election substance and legitimacy?

It could be argued that civil war - defined as the resort to violence in a country to settle political differences - is already rampant in parts of Iraq.

No one knows how the remoteness of candidates, many of whom have withheld their identities for fear of assassination, will affect voters.

Many Iraqis also view their leaders as incapable of dealing with their pressing concerns - security, unemployment, inadequate infrastructure.

The behaviour of US forces - perhaps staying too close to polling stations and scaring away voters - could have an influence.

By contrast, the calls for a boycott may have less impact than feared.

There is even a suggestion that the Iraq's once powerful military establishment - the backbone of the anti-US insurgency in the Sunni Triangle and a counter-balance to Baathist power - may vote so they don't lose even more of their status after the US disbanded the army.