A signature on a candidate's petition is invalid if the signer:
(1) signed the petition on or before general primary election day or, if a runoff primary is held for the office sought by the candidate, on or before runoff primary election day; or
(2) voted in the general or runoff primary election of a political party that made a nomination, at either primary, for the office sought by the candidate.
Official text of the Texas Election Code as published by the Texas Legislative Council.