Egypt, the heart of the Arab world and its most populous country, goes to the polls Wednesday and Thursday to elect a new president, a leap into the unknown after 60 years of military coups and stage-managed elections.

All that came to an end with the February 2011 downfall of the dictatorial Hosni Mubarak after 30 years of repressive rule in a pro-democracy revolution that's changing the face of the Middle East.

Campaigning ended Monday. If this week's voting fails to produce an outright winner, there will be a runoff no later than July 1.

That should end a military-led transitional period since Mubarak's downfall, produce a new constitution and, hopefully, a new era in Middle Eastern politics.

The long-awaited presidential election should be a turning point in Egypt's fragile transition from dictatorship to democracy.

But there are many pitfalls. The interim governing body, the Supreme Council of the Armed Forces, or SCAF, is the rearguard of the ancien regime.

The generals, who threw Mubarak to the mob when they saw the power of the Arab street, have repeatedly sought to undermine the pro-democracy drive, and largely failed.

They would have preferred no election, but they're stuck with it.

Meantime, there's a growing rift, still, between the generals and the emerging political parties, effectively banned under Mubarak, who will replace them when the army relinquishes power, as it pledged it will, June 30.

The electioneering has proceeded without major mishap, although there was a surge of violent protests against the generals a few weeks back. If the military balks at stepping down after the election, there will be blood on the streets again.

So there's a lot riding on the voting process that begins Wednesday, not just for Egypt but the whole Arab world and the Middle East, from the Atlantic Ocean of the Indian Ocean, that's passing through a critical phase of immense import.

Islamists made sweeping gains in parliamentary elections held between November and January, the first ballot that was anywhere near free since Gamal Abdel Nasser overthrew the corrupt of King Farouk July 26, 1952.

But SCAF still holds the reins of power. It has vowed it will hand over power to civilian hands, but whether that happens in the fullest sense remains to be seen.

Many Egyptians suspect the generals might try to renege on that promise.

"The reality is that the SCAF is a dominant, unspoken presence not only in the presidential elections but in its new political system," British commentator Peter Beaumont reported from Cairo.

"All parties are forced to negotiate the generals' continuing presence -- and, increasingly, they are judged by how they do that."

There are growing concerns the Muslim Brotherhood, the biggest and most influential of the Islamist parties which dominates parliament, seeks to monopolize power.

"Perhaps even more toxic, however, is the widespread charge -- also leveled by some younger Brotherhood activists -- that by avoiding a confrontation with the generals, even in the midst of violent clashes late last year, it has at best let SCAF off the hook, at worst, somehow collaborated with it," Beaumont wrote in Britain's Observer newspaper.

"But the desire among the Islamist parties to avoid conflict with the generals runs deep."

The key contenders are Abdel Moneim Abul Fotouh, 60, a moderate Islamist and physician. He quit the Brotherhood to run as an independent and is widely tipped as favorite.

He's backed by Salafist Islamists and the Gamaa al-Islamiya, designated a terrorist group by the United States and the European Union.

He's a front-runner along with Amr Moussa, 75, a former foreign minister under Mubarak and most recently secretary-general of the Arab League.

Moussa's seen as the most experienced of the candidates, but his history as part of Mubarak's clique is likely to limit his support among Islamists and the young revolutionaries who toppled Mubarak.

Ahmed Shafiq, 70, is a former air force commander and an ally of Mubarak, who named him president in a desperate bid to appease the mob shortly before his downfall.

He's seen as the generals' choice, which could kill his chances of winning the election.

Mohammed Morsi was selected as the Brotherhood's candidate after its first choice, veteran Islamist Khairat al-Shater, was disqualified because of a criminal conviction.

The 60-year-old conservative has no charisma and isn't expected to do well.