Perhaps this is why;
In 1971 and 1972, Smith was embroiled in the Sharpstown scandal stock fraud scheme, which eventually led to his downfall. Smith lost his third-term bid for the governorship of Texas to Dolph Briscoe of Uvalde in the Democratic primary in 1972. He ran a distant fourth in the primary, behind Briscoe, women's activist Frances "Sissy" Farenthold of Corpus Christi, and Lieutenant Governor Ben Barnes, formerly of Comanche County.
https://en.wikipedia.org/wiki/Preston_Smith_(governor)#Political_career
