Local businessman Jack Yan proposed that Robertson's campaign be turned into a political party in 2001, a decision that she agreed to the following year after finding that most parties in Parliament generally did not support a reduction. Robertson took initial steps toward achieving the membership number required. Yan initially served as president and designed the logo and marketing collateral, but lived in Europe in the northern summer of 2002, became less involved on his return, and was replaced.
The 2002 policies were centrist to conservative, including the toughening of the Crimes Act 1961 and reforming Parliament and the select committee structure. In addition to the reduction of MP numbers, the party also supports making referendums mandatory for all constitutional changes.
The Electoral Commission accepted the party's official registration on 14 April 2005. It put forward a party list of two people: Robertson and Ramasmy Ramanathan.
In the 2005 elections, the 99 MP Party gained 0.03% of the vote. Shortly afterwards, Margaret Robertson announced plans to step down.
On 16 March 2006, the Parliament of New Zealand passed the first reading of New Zealand First MP Barbara Stewart's private members bill, to cut the number of MPs to 100. A number of parties indicated though that their support was for it to go to select committee, at which public submissions could be heard. However, but the bill was defeated at its Second Reading on 8 November 2006. As of 2017 , the size of parliament remains at least 120.
In September 2006, the party was deregistered, having failed to provide evidence of the necessary 500 members.