District branches were in place by April 1959, and the party gained representation in the Belize City Council in December 1958, when Fuller, Staines, Rogers and Claire Gill were elected, though Meighan and Floss Cassasola campaigned as independents and cut loose from the Party for their behaviour.
Another spat came when the Benque Viejo branch set itself up as the Western Independent Party under Juan Gongora and sought affiliation with the NIP, which it agreed to.
Phillip Goldson was appointed by the Governor and subsequently assumed the post of Party Leader from Fuller, who died in March 1962.
In the December 1962 City Council elections, the NIP began a run of complete shutouts that lasted until the UDP's 6-3 triumph in 1974.
General elections of 1965 and 1969 (in which the NIP collaborated with the breakaway PDM) saw Phillip Goldson retain both times and Edwin Morey earning a surprise victory in 1965.