Nonsense. Republican John Tower was elected Senator from Texas in 1961, when Perry was 11 years old. Republican Bill Clements was elected Gov of Texas in 1979, 10 years before Perry changed parties.
Republicans did get elected at the statewide level, but the Democrats held majorities in both houses until the late 90's. When Perry backed Gore in 88, the Texas Senate was 25 Dem and 6 GOP, whereas the Texas House was 90 Dem and 60 GOP. It was only in 2003 that the GOP held both chambers of the Texas statehouse, decisively ending over 100 years of Democratic post-Reconstruction dominance.
In fact, one of Bush’s talking points in the 2000 election was the fact that he was curbed by Democratic majorities in the Texas statehouse, but knew how to reach across the aisle in order to make deals.