Texas Election Code - ELEC § 191.001. Parties Required to Hold Presidential Primary Election

(1) in the presidential election year, the party is required by this code to nominate its candidates for state and county offices by primary election;

(2) a presidential primary election is authorized under national party rules;  and

(3) before January 1 of the presidential election year, the national party has determined that it will hold a national presidential nominating convention that year.