Situala joined Nepali Congress in 2033 BS. He became Jhapa district vice-president of the party in 2043 BS. Situala worked as the coordinator and acting district committee of the party during the 2046 BS people’s movement. He became Jhapa district party president after the restoration of the multi-party democracy.
In 2056 BS, Sitaula became chief of the party's central coordination committee. He was elected as a central committee member for the first time through the tenth general convention. Sitaula was the candidate for the president in the 13th general convention of the party.
Sitaula contested the House of Representatives member from then Jhapa-1 (now Jhapa-3) in the elections held in 2048 BS. He was defeated by DronacharyaChhetri of CPN-UML in the elections.
He emerged victorious in the 2050 BS by-elections but got defeated in elections held in 2051 BS. He got elected again in 2056 BS and 2070 BS. Sitaula was defeated by Purna Singh Rajbanshi of Maoist in 2064 BS and by Rajendra Lingden of RPP in the 2074 BS polls.
Sitaula was State Minister of Industry, Commerce and Supplies during the Girija Prasad Koirala-led government in 2057 BS and Home Minister in 2063 BS. He served as the Deputy Prime Minister and Minister for Defence and Minister for Law and Justice in the government led by Baburam Bhattarai.