The Financial Times' David Crow reports that the drugstore's lawyers are looking for a way to close 40 Theranos locations in Walgreens' outlets.
The wellness centers, where people can have their blood tested for everything from sexually transmitted diseases to cholesterol levels, are located in Arizona and California.
Earlier this month, the Wall Street Journal reported that Walgreens gave Theranos 30 days to resolve the problems found with its lab in California or face termination of the partnership.
Losing the partnership would be a major setback for Theranos, costing it most of its retail locations. The wellness centers are part of a pilot program, and Walgreens has said publicly that it doesn't have any immediate plans to expand that.
Walgreens declined to comment to Business Insider, while Theranos didn't immediately reply to a request for comment.
Last month, the Centers for Medicare and Medicaid Services said it found problems with the northern California lab including some that "pose immediate jeopardy to patient health and safety." Theranos has since submitted a plan of correction to CMS.
The Financial Times also reported that Walgreens executives don't think Theranos will be able to resolve its regulatory issues and are getting frustrated with the amount of negative attention cast on the company because of the deal.
Most of Theranos' blood tests are run out of its Arizona lab, including about 95% of all Walgreens-related tests. The Arizona lab was not included in the CMS warning.
Read the full Financial Times story here (behind a paywall).