Upon his entry, Morrow's chief opponent was former U.S. Senator Joseph S. Frelinghuysen Sr., who had announced his candidacy even before Edge's appointment and resignation. Frelinghuysen stressed his campaign as a challenge to the establishment, identifying Morrow as an ally of the "Baird-Larson-Kean" group which controlled all of New Jersey's statewide offices, which Frelinghuysen termed "machine domination." Frelinghuysen additionally suggested Baird's appointment had been orchestrated by the machine to allow Morrow to avoid controversial votes, such as on the Smoot-Hawley Tariff, which Frelinghuysen supported. State party chairman E. Bertram Mott responded that the state committee took no official side in the primary, though "a great majority ... [were] in favor of Mr. Morrow for the nomination."
