Wangsu contested the Kanubari seat in the 2009 Arunachal Pradesh Legislative Assembly election. He stood as a People's Party of Arunachal candidate, obtaining 4,189 votes (46.30%) and finishing in second place behind the Indian National Congress leader Newlai Tingkhatra.[3]
He again contested the Kanubari seat in the 2014 Arunachal Pradesh Legislative Assembly election, standing as an independent.[1] He was again defeated by Tingkhatra, finishing in third place with 2,756 votes.[4] Tingkhatra died soon after the results were declared. Wangsu stood as the Indian National Congress candidate in the 15 October 2014 by-poll to fill the vacant Kanubari seat.[2][5][6] He was elected with 5,231 votes.[7]