Egyptians began voting on Monday, May 26, in a presidential election expected to sweep former army chief Abdel Fatah al-Sisi into office, reviving rule by strongman three years after Hosni Mubarak's downfall, Reuters reports.

Voters cast ballots at heavily guarded polling stations from 9.00 a.m. (2.00 a.m. ET). Sisi, who deposed the Muslim Brotherhood's Mohammed Mursi last July, faces only one challenger in the two-day vote: the leftist politician Hamdeen Sabahi.

Widely regarded as Egypt's de facto leader since he toppled Morsi following mass protests, Sisi faces manifold challenges including an economy in crisis and an Islamist insurrection that has spiraled since Morsi's downfall.

As voting began, a homemade bomb exploded outside a polling station in the city of El-Mahalla El-Kubra, north of Cairo, state TV reported. No casualties were reported, according to Reuters.

Supporters regard Sisi, who resigned from the military earlier this year, as a decisive figure who can stabilize Egypt, a strategic U.S. ally in the heart of the Arab world.

His opponents, mostly in the Islamist opposition, say he is the mastermind of a coup that robbed Egypt's first freely elected leader of power.

They fear Sisi will rule Egypt with an iron fist just like other former military men did, and that he will protect the political and economic interests of the generals and businessmen who amassed fortunes before the 2011 uprising which toppled Mubarak but remain influential.

The Brotherhood has called for a boycott of the vote it has described as a farce.

Security forces have largely driven the Brotherhood underground after hundreds were killed and thousands arrested. More than a thousand Brotherhood supporters have been sentenced to death on charges including inciting violence after the army overthrew Mursi.

Since the army overthrew the king in 1952, Egypt has been ruled by a series of military men including Gamal Abdel Nasser and Anwar Sadat, a pattern briefly interrupted by Mursi's one year in office.

Monitors from the European Union and U.S.-funded Democracy International are observing the vote, and more than 400,000 members of the security forces have been deployed to secure polling stations across the country.

Sisi secured 95 percent of votes cast in advance by Egyptians overseas, but an opinion poll by the Washington-based Pew Research Center suggests a more mixed picture inside Egypt, with Sisi viewed favorably by 54 percent and unfavorably by 45 percent.

The Muslim Brotherhood and its Islamist allies have vowed to escalate a "revolutionary wave" this week, though it has been many months since they were able to mobilize large numbers in the streets. The Brotherhood has urged its supporters to boycott the election.