Heintzleman submitted his resignation on December 18, 1956. His letter of resignation explain his departure by pointing out that he "had forty-six years of public service" and desired "to retire to less strenuous work". The timing, three months before the end of his term, was occasioned by the outgoing governor's desire to allow for his replacement to be in place before the next territorial legislature convened on January 28, 1957. Heintzleman's resignation became effective on January 4, 1957, when Territorial Secretary became Acting Governor. A permanent replacement was not named until May 9, 1957, when President Eisenhower nominated Michael Anthony Stepovich.