Leaders of the country's second-largest teachers union have authorized its member to strike if schools don't take proper steps to protect teachers' health.
The American Federation of Teachers, which represents 1.7 million school employees, says it will support any local chapter that decides to strike over reopening plans.
The union will also provide local chapters access to its financial and legal resources as plans are laid for the returns to campus.
Besides requiring masks, the union is also pushing schools to keep people 6 feet apart, keep all buildings and buses clean and to make accommodations for teachers at greater risk of health problems if they contract COVID-19.