Egyptians vote Wednesday in a historic presidential election that pollsters say is too close to call, with a choice of candidates touting radically different visions for the country's future.

No outright winner is expected from the two-day poll, so a runoff is scheduled for June 16-17 between the two top finishers. The winner will be announced June 21.

Four main contenders have emerged from a field of 13 on the eve of Egypt's biggest test yet of its transition from decades of military dictatorship to democratic civilian rule.

Two of the front-runners served under former president Hosni Mubarak and have promised to restore stability and ensure secular rule.

Former foreign minister and Arab League chief Amr Moussa, a liberal who has been a public figure for years, seemed to be leading the pack until the last few days. But recent polls have shown the rise of Ahmed Shafiq, a former Air Force commander and Mr. Mubarak's last prime minister, who enjoys the support of Egypt's powerful military.

The two are running against a pair of Islamist candidates.

Mohamed Morsi, who represents Egypt's powerful Muslim Brotherhood, entered the race late but has benefited from the group's effective political machine, which has campaigned door-to-door.

His rise has come at the expense of the moderate Islamist candidate, Abdel Moneim Aboul Fotouh. A former Brotherhood member, Aboul Fotouh's campaign is geared to a wide range of Egyptian voters, from liberals to hardline Salafi Muslims and Christians.

But analysts say such a broad appeal has grown harder to maintain as rhetoric sharpens on all sides.

Shafiq has risen in the polls by targeting a population frustrated with Egypt's turbulent transition, plagued by violent clashes, an ever-increasing wave of violent crime and an economy in disarray.

Egypt's widespread lawlessness has overshadowed daily life since the revolution that began in January 2011. It is the most prominent issue in the presidential race.

A victory for either of the secularist candidates would mark a significant turn from parliamentary elections just six months ago when more than 70 percent of voters cast ballots for Islamist parties.

The head of Egypt's independent Baseera polling firm told the French news agency that 33 percent of those surveyed on May 16 were still undecided.