Legislative seats are divided equally between Muslim and Christian groups, despite Christians estimated to represent only about a third of the population now. By convention, the office of the prime minister is held by a Sunni Muslim, the office of the president is held by a Christian Maronite, and the office of speaker of the parliament is held by a Shiite Muslim. This is a more rigid allocation of power than in Northern Ireland where, for example, the leader of any party, whether nationalist or unionist, that achieved the highest share of the vote could become the first minister (i.e. the prime minister).