It turns out that Sam Brownback is a smarter, more nuanced guy that I had imagined:
The premise behind the question seems to be that if one does not unhesitatingly assert belief in evolution, then one must necessarily believe that God created the world and everything in it in six 24-hour days. But limiting this question to a stark choice between evolution and creationism does a disservice to the complexity of the interaction between science, faith and reason.
I don’t agree with him, but I’m glad that he at least has a reasonable perspective.