  On an explicit example of the Siegel superparticle we study an alternative to
the harmonic superspace approach. The latter seems to be the only method for
quantizing infinitely reducible first class constraints currently available. In
an appropriately extended phase space, the infinite ghost tower is effectively
canceled by that coming from the sector of auxiliary variables. After a proper
BRST treatment the theory proves to be of rank two which correlates well with
the results obtained earlier within the framework of the harmonic superspace
approach. The advantage of the novel technique, however, is the existence of an
explicit Lagrangian formulation and the standard spin--statistics relations
which hold for all the variables involved.
