The commissioner shall, within sixty (60) days after the filing of a petition for referendum, and subject to a finding by the Tennessee dairy promotion committee that the petition is properly filed, determine by referendum whether the producers assent to the proposed assessment, change in assessment or termination of an existing assessment. The producers shall be deemed to have assented to the assessment, change in assessment or termination of an existing assessment if a simple majority of those voting assent to the assessment, change in assessment or termination of an existing assessment by affirmative vote.