The NPI was founded in June 2001, and was soon joined by British Columbian Members of Parliament Libby Davies and Svend Robinson.
The NPI originally called for the NDP to disband and form another, more left wing, party under a different name with the participation of social movements.
It was said that this would have followed the path set by the NDP when it was created in 1961 by its predecessor party, the Cooperative Commonwealth Federation, and labour unions, but the NPI did not propose a formal merger, but a disbanding.
At the NDP convention held in Winnipeg in November 2001, opponents of the initiative used that lack of detail to defeat the proposal.
With Layton's election the NPI became less vocal and formally dissolved in early 2004, with a concluding public meeting being held on February 22.