  We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to
the removal of natal material in the early evolution of massive star clusters.
Despite previous work suggesting that massive star clusters clear out their
natal material before the massive stars evolve into the WR phase, WR stars have
been detected in several emerging massive star clusters. These detections
suggest that the timescale for clusters to emerge can be at least as long as
the time required to produce WR stars (a few million years), and could also
indicate that WR stars may be providing the tipping point in the combined
feedback processes that drive a massive star cluster to emerge. We explore the
potential overlap between the emerging phase and the WR phase with an
observational survey to search for WR stars in emerging massive star clusters
hosting WR stars. We select candidate emerging massive star clusters from known
radio continuum sources with thermal emission and obtain optical spectra with
the 4m Mayall Telescope at Kitt Peak National Observatory and the 6.5m MMT. We
identify 21 sources with significantly detected WR signatures, which we term
"emerging WR clusters." WR features are detected in $\sim$50% of the
radio-selected sample, and thus we find that WR stars are commonly present in
massive star clusters currently emerging. The observed extinctions and ages
suggest that clusters without WR detections remain embedded for longer periods
of time, and may indicate that WR stars can aid, and therefore accelerate, the
emergence process.
