Laboratories around the country are now facing potential shortages of key materials and chemicals needed to run tests for the novel coronavirus, as cases spread to more than two-thirds of the states and the global pandemic strains testing resources even further.

Some lab directors say they are already beginning to run low of the supplies needed to extract RNA from nasal swabs, a crucial initial step that is separate from the millions of test kits that the federal government has promised to ship to every state. Others say they are weighing whether to borrow some materials from other research labs that aren’t involved in creating or running coronavirus tests.