As Apple prepares to release the latest generation of its iPhone this fall, it is starting to feel the pinch Android makers have been feeling for months from the global chip shortage. Still, new survey results suggest the chip crunch is hitting other manufacturers of high-end phones such as Samsung Electronics much harder, and the problems are becoming more widespread, at least in the U.S.

In a survey of 37 sales representatives at wireless retail stores across the U.S., 26 of them, or 70%, reported shortages of smartphone inventory in August, up from 45% in June and 28% in May, according to Wave7 Research, a firm whose monitoring of retailers is closely watched by the wireless industry. Notably, the shortages were more pronounced for Samsung and other makers of Android-powered devices than for iPhones, and they are expected to persist through the holiday season, said Jeff Moore, a principal at the research firm.