 Kunze kwenzvimbo yake yemakurukota, Leimena akabvuma kutungamira Pemuda Indonesia Maluku PIM, sangano rinotsigira Indonesian Ambonese rakaumbwa naJohannes Latuharhary. Nepo vose vari vaviri Leimena naLatuharhary vairemekedzwa, vakanga vane kudzora kuduku pamabasa ePIM. Leimena akanga ari muJakarta mumazuva okutanga echimurenga, asi akatamira pamwe chete nevamwe vose vemakurukota aSjahrir muna 1946 kuYogyakarta sezvo Jakarta yakanga ichiwedzera kudzorwa nemaDutch. Leimena akanga ari nhengo inokosha yeboka reIndonesia rokukurukurirana muzvibvumirano neDutch. Aive chikamu chemumiriri weIndonesia kuLinggadjati Chibvumirano chaNovember 1946 uye Chibvumirano cheRenville chaNdira 1948 panguva iyo, Leimena akataura, divi reIndonesia rakabvuma mazwi echiDutch pasi pekumanikidzwa kweAmerica. Pashure peOperation Kraai yeDutch, Leimena akapukunyuka kubatwa uye akapinda hurukuro muJakarta nevamiriri kubva kumatunhu ehurumende yeUnited States yeIndonesia muna Ndira 1949. Munguva RoemVan Roijen Agreement, Leimena zvakare muchirongwa nhaurirano, uye iye mberi muchirongwa DutchIndonesian Round Table Conference muThe Hague, vachitungamirira Indonesia kuti uto nhume. 