Miss. Code Ann. § 23-15-771

At the state convention, a slate of electors composed of the number of electors allotted to this state, which said electors announce a clearly expressed design and purpose to support the candidates for President and Vice-President of the national political party with which the said party of this state has had an affiliation and identity of purpose heretofore, shall be designated and selected for a place upon the primary election ballot to be held as herein provided.