Sitta, a member of the majority Chama Cha Mapinduzi party, served as a member of parliament from 1975 to 1995 and was director-general of the Tanzania Investment Centre. Later he served again as an MP, representing Urambo Mashariki.[4]
He was elected to succeed Pius Msekwa as Speaker of the National Assembly on 26 December 2005.[4] He was appointed to the Cabinet as Minister of East African Cooperation in 2010.