Following early discussion on Complexity of maximizing the number of models in a parametric formula it seems that the problem discussed is equivalent to a complete problem in $\mathrm{NP}^{\mathrm{PP}[1]}$, that is, the class of problems solvable in nondeterministic polynomial time with at most one call to a $\mathrm{PP}$ oracle (a $\mathrm{PP}$ oracle accepts if at least half of its nondeterministically possible runs accept).
I've not seen this class mentioned in the literature, but I probably missed something. I was wondering what is known about it.