In October 2004, Kassar was appointed minister of economy and trade in the cabinet led by prime minister Omar Karami, replacing Marwan Hamadeh as economy minister.[1][11] His tenure lasted until the year 2005, when Karami resigned from office due to the pressures exerted by Lebanese people as a protest over the assassination of Rafik Hariri.[12] Kassar was succeeded by Demianos Khattah in the post.[4][11] Later Kassar served as the minister of state in the cabinet led by prime minister Saad Hariri from November 2009 to 2011.[5] Kassar was one of the cabinet members appointed by the Lebanese president Michel Suleiman.[13]