Supporters have set forth possible UNPA implementations, including promulgation of a new treaty; creation of a UNPA as a subsidiary body of the UN General Assembly; and evolution of a UNPA from the Inter-Parliamentary Union or another non-governmental organization. Several proposals for apportionment of votes have been raised to address disparities in population and economic power of UN members. CEUNPA advocates initially giving the UNPA advisory powers and gradually increasing its authority over the UN system. In 2018, CEUNPA's co-founders Jo Leinen and Andreas Bummel published a 420-page book on the history, current relevance and future implementation of the idea titled "A World Parliament: Governance and Democracy in the 21st Century".