Tex. Election Code § 174.065

(a) The state executive committee of a political party may adopt a rule requiring the county chair to be the permanent chair of the county convention or requiring the senatorial district executive committee member or chair of the district executive committee, as applicable, to be the permanent chair of the senatorial district convention, unless the person is absent or declines the position. If a rule is not adopted under this subsection, the county chair is the temporary chair of a county convention held under this subchapter. If a senatorial district is situated in more than one county, the senatorial district executive committee member from each county is the temporary chair of the senatorial district convention held in the territory that the committee member represents unless the state executive committee has adopted a rule under this subsection. If a senatorial district is not situated in more than one county, the chair of the district executive committee is the temporary chair of the senatorial district convention unless the state executive committee has adopted a rule under this subsection.

(b) If the person designated as chair by Subsection (a) is absent or declines the position, a delegate to the convention may act as temporary chair.

(c) The chair shall call the convention to order and deliver the lists of delegates prepared under Section 174.027 to the convention.

(d) The convention shall select a convention chair, if the person listed in Subsection (a) is not the permanent chair, is not present, or has declined the position, and a convention secretary from among the delegates present. The convention may select any other officers considered necessary to conduct the convention's business.