Texas Election Code - ELEC § 191.002. Qualifying for Place on Ballot

(a) Candidates qualify to have their names placed on the presidential primary election ballot in the manner provided by party rule, subject to this section.

(b) If party rules provide for the filing of applications or signature petitions to qualify candidates for a place on the ballot, the filing deadline may not be later than the regular filing deadline for candidates in the general primary election.  A signature on a candidate's petition is not valid unless it is that of a registered voter and is accompanied by the signer's residence address, including county, and voter registration number.

(c) A person may not sign petitions supporting more than one presidential candidate in the same primary, and, if a person does so, the person's signature is void as to all petitions the person signs.