Scientists are better at agenda-setting, helping with the “problem emergence” thing – they tend to not (want to) get involved in the policy battles, because they don’t have the training, resources, appetite, and it is a massive reputational risk.
There is a vast vast literature on science and policy interface of course. One of my favourite recent ones is Hess, D. 2014. When Green Became Blue: Epistemic Rift and the Corralling of Climate Science. Political Power and Social Theory, Vol. 27, pp.123-153.