During his term as Chief Minister, N'Jie was involved in early negotiations with the Senegalese government over the Gambia's long-term future. He remained as Chief Minister until the 1962 election, when the PPP won a clear victory, although N'Jie retained his New Town East seat. N'Jie became the Leader of the Opposition, while Dawda Jawara became the first Prime Minister of the Gambia. The United Party challenged the election results in the courts, alleging that the register of voters had been invalid. The claim was upheld by the West African Court of Appeal in April 1963, but N'Jie dedicated much of his time until Gambian independence trying to persuade the British government to call a new election. In his absence, the United Party went into decline, with a number of its members joining the PPP.