Within the politics stream of the Multiple Streams Approach there are party ideology, national mood and balance of interests [presumably akin to the relative power of coalitions in the policy subsystem?].
“aggregate position of relevant interests, including arrayed advocacy groups and other actors interested in a particular problem.”
(Jones et al. 2016:16)
Jones, M. Peterson, H., Pierce, J. Herweg, N., Bernal, A., Lambert Raney, H. and Zahariadas, N. 2016. A River Runs Through It: A Multiple Streams Meta-Review. Policy Studies Journal, Vol. 44, pp.13-36.