According to its constitution, Egypt is a republic governed by an elected president and bicameral legislature, with the upper house or Senate newly established during the year. Presidential elections were held in Challengers to incumbent President Abdel Fattah al-Sisi withdrew ahead of the election, citing personal decisions, political pressure, legal troubles, and unfair competition; in some cases they were arrested for alleged violations of candidacy rules. Domestic and international organizations expressed concern that government limitations on association, assembly, and expression severely constrained broad participation in the political process. Observers noted restrictions on freedom of peaceful assembly, political association, and expression significantly inhibited the political climate surrounding the elections. The Public Security Sector Police are responsible for law enforcement nationwide.