Richardson aive mukwikwidzi wekusarudzwa kweDemocratic musarudzo yemutungamiri wenyika ya2008 asi akadonha musi waNdira 10, 2008 mushure mekuratidzwa kusingafadzi mumakwikwi ekutanga uye e caucus. Pasinei nenhau yake refu noushamwari nemhuri yaClinton, Richardson akatsigira Barack Obama
nokuda kwekusarudzwa kweDemocratic musi waMarch 21, 2008, panzvimbo paHillary Clinton. Mutsinhiri uye mubatsiri waClinton James Carville akaenzanisa Richardson naJudhasi Iskarioti nokuda kwechiito chacho. Richardson akapindura munyaya ye"Washington Post", achinzwa "achimanikidzirwa kuzvidzivirira [pachake] pakurwiswa kwomunhu uye kupomerwa kusina hwaro".