  The hypothesis that CAK-type line driving is responsible for the large
observed Wolf-Rayet (W-R) mass-loss rates has been called into question in
recent theoretical studies. The purpose of this paper is to reconsider the
plausibility of line driving of W-R winds within the standard approach using
the Sobolev approximation while advancing the conceptual understanding of this
topic. Due to the multiple scattering required in this context, of particular
importance is the role of photon frequency redistribution into spectral gaps,
which in the extreme limit yields the statistical Sobolev-Rosseland (SSR) mean
approximation. Interesting limits to constrain are the extremes of no frequency
redistribution, wherein the small radii and corresponding high W-R surface
temperature induces up to twice the mass-loss rate relative to cooler stars,
and the SSR limit, whereby the reduced efficiency of the driving drops the mass
flux by as much as an order of magnitude whenever there exist significant gaps
in the spectral line distribution. To see how this efficiency drop might be
sufficiently avoided to permit high W-R mass loss, we explore the suggestion
that ionization stratification may serve to fill the gaps globally over the
wind. We find that global ionization changes can only fill the gaps
sufficiently to cause about a 25% increase in the mass-loss rate over the local
SSR limit. Higher temperatures and more ionization states (especially of iron)
may be needed to achieve optically thick W-R winds, unless strong clumping
corrections eliminate the need for such winds.
