Tex. Election Code § 202.005: NOMINATION BY CONVENTION.

A political party's nominee for an unexpired term must be nominated by the appropriate party convention if:

(1) the political party is making nominations by convention for the general election in which the vacancy is to be filled; and

(2) the vacancy occurs on or before the fourth day before the date the convention convenes.

Acts 1985, 69th Leg., ch. 211, Sec. 1, eff. Jan. 1, 1986.