|Tammam Salam (at right) with his late father Saeb Salam in 1998|
The Prime Minister must always be a Sunni. Typical of Lebanon's tradition of the politics of powerful families, Tammam Salam is the son of Sunni leader and frequent Prime Minister Saeb Salam (1905-2000), who played a key role as a Sunni leader from 1942 until overshadowed by Rafiq Hariri in the 1990s, and who served as Prime Minister six times from 1952 to 1973, and as a key Sunni leader in the civil war years. Tammam Salam has been mentioned as a possible Prime Minister on earlier occasions. The family is from Beirut (Miqati was from Tripoli, and there has long been rivalry between the key Sunni families of Tripoli, such as the Karamis, and the Sunnis of Beirut, such as the Salams, over leadership of the Sunni community.
Saeb Salam's father was a prominent figure in Ottoman and French Mandate times, so the family tradition of leadership is an established one.
Articles and analysis here and here; a profile here.