Egyptians are preparing to head to the polls in their first free presidential election, 15 months after ousting Hosni Mubarak in the Arab Spring uprising.
Fifty million people can vote, and security is likely to be tight.
The Supreme Council of the Armed Forces, which assumed presidential powers in February 2011, has promised a fair poll followed by civilian rule.
The election pits Islamists against secularists, and revolutionaries against Mubarak-era ministers.
The frontrunners are Ahmed Shafiq, a former commander of the air force and briefly prime minister during February 2011 protests, Amr Moussa, who has served as foreign minister and head of the Arab League, Mohammed Mursi, who heads Muslim Brotherhood's Freedom and Justice Party and Abdul Moneim Aboul Fotouh, an independent Islamist candidate.
The four men generally regarded as the front-runners are all either Islamists or former ministers who served in the old regime.
A run-off vote is scheduled for 16 and 17 June if there is no outright winner.