“evolving”. Code word for abandoning your morals.
The word "morals" -- or "principles", for that matter -- is anathema to most politicians. In this case, the only criterion that will be considered is whether the politician thinks they can garner more votes by supporting homosexual "marriage" than by not. Morality, honor and respect for principles have nothing to do with the political calculation.
Enthusiastic as she is for mass baby-killing, she never had any morals to lose.