Miss. Code § 23-15-1085
The chairman of a party's State Executive Committee shall notify the Secretary of State if the party intends to hold a presidential preference primary. The Secretary of State shall be notified prior to December 1 of the year preceding the year in which a presidential preference primary may be held pursuant to Section 23-15-1081. Upon such notification, the Secretary of State shall issue a proclamation setting every party's congressional and senatorial primary elections that are to be held in the year in which the presidential preference primary is to be held on the date provided for in Section 23-15-1083. Once the Secretary of State has issued a proclamation pursuant to this section, the date of the congressional and senatorial primary elections shall not be changed.
Miss. Code § 23-15-1085