An early tour of Cairo polling stations suggested authorities would again struggle to get more people to cast their ballots. The same pattern emerged in Egypt's second city, Alexandria, Reuters reporters said.
For Sisi, who toppled President Mohamed Mursi of the Muslim Brotherhood last year after mass protests against his rule, the stakes are high.
Poor backing in the election in his deeply divided country would mean Sisi's legitimacy as head of state of the Arab world's most populous nation would be harmed at home and abroad.