The UP was seen as the main opposition party, but it lost power from 1965 to 1970. In 1975, the National Convention Party (NCP) was formed by Sheriff Mustapha Dibba, and became the new main opposition party to the PPP's dominance. Both the PPP and NCP were ideologically similar, so in the 1980s a new opposition party emerged, in the form of the radical socialist People's Democratic Organisation for Independence and Socialism (PDOIS). However, between the 1966 and 1992 elections, the PPP was "overwhelmingly dominant", winning between 55% and 70% of the vote in each election and a large majority of seats continually.