I did think it went back specifically to the Peel Commission Report in England (1937). That also included a British Mandate that would include Jerusalem. I think of that as the 'tripartite solution'.

An updated version of it could allow for a strictly Jewish state, a strictly Muslim state, and a 'democracy of the willing', a secularly governed polity that would include Jerusalem. If the three polities could bring themselves to share in some way a economic process, that would provide an impetus towards peaceful coexistence.