Tex. Elec. Code § 182.003

To be entitled to have the names of its nominees placed on the general election ballot, a political party making nominations under this chapter must file with the county clerk, not later than the 75th day after the date of the precinct conventions held under this chapter, lists of precinct convention participants indicating that the number of participants equals at least three percent of the total number of votes received in the county by all candidates for governor in the most recent gubernatorial general election.