The Koch network once loved Mike Pence. Now it’s playing the field.

Art Pope, the former chair of Americans for Prosperity and a Raleigh, N.C.-based Republican donor, said that the decision by the group to endorse a Trump rival “was not intended to benefit one particular candidate at this time.” Instead, he said, the goal was “to find the best candidate, and more importantly, to be the best president of the United States on the issues that Americans for Prosperity champions.”

Pope, who attended the…