In the 1972 election, his loyalty to the Alliance Party was rewarded with the safe seat of Vanua Levu and Lau formerly held by his relative, Vijay R. Singh. After the election he was appointed the Minister of Health. After Vijay R. Singh resigned as leader of the Indian Alliance, following his appointment as Speaker of the House of Representatives in 1976, the leadership of the Indian division of the Alliance passed on to James Shankar Singh. Following the shock defeat of the Alliance Party in the March 1977 election, the Party adopted a more emphatically ethnic Fijian policy, in order to regain its lost Fijian votes. With the rise of Ahmed Ali, who was prepared condone the new pro-Fijian policies of the Alliance Party, James Shankar Singh found himself being alienated from the party's leadership, and after he failed to get the party ticket for the 1982 election, resigned from the Alliance on the grounds of "irreconcilable differences" with Ratu Sir Kamisese Mara.
