As some federal employees face pressure to return to work, U.S. senators from Maryland and Virginia are urging agency heads to continue to encourage working from home.

Returning to federal workplaces while COVID-19 cases continue to mount in many parts of the country threatens to “erase the progress made against the virus and endanger the health and safety of federal employees and everyone else in an agency’s region,” says a new letter from Democratic senators Chris Van Hollen, Ben Cardin, Mark Warner, and Tim Kaine. It was sent to acting directors at the Office of Personnel Management and the Office of Management and Budget.

The letter references April guidance from the agencies that encourages federal employers to follow their state or locality’s reopening schedule.

“Agency heads should begin transitioning federal operations to align with a geographic area’s respective phase, while also accounting for agency operational needs, as appropriate and applicable,” the guidance says. Eighty-five percent of the federal workforce is outside the Washington area.

The four Democratic senators say that guidance has resulted in some federal employees in the DC region being called back to the office while the coronavirus remains a threat. Their letter suggests following in the footsteps of local governments that have kept most of their employees at home.

“Unlike these federal agencies, governments in Maryland, Virginia, and the District continue to utilize liberal telework policies and limited office capacity for public sector workers,” the letter says.

D.C. Mayor Muriel Bowser, Maryland Gov. Larry Hogan, and Virginia Gov. Ralph Northam sent a similar letter in April to OPM Acting Director Michael Rigas calling for a continued federal telework policy.

There are no federal laws that require employers — in either the public or private sectors — to take certain steps to protect workers from the coronavirus. The federal government has only issued optional guidelines.

Virginia is the only U.S. state considering its own statewide health regulations for workplaces during COVID-19, but those regulations are still being refined by Virginia’s Department of Labor and Industry, and they must be approved by a board that includes employer representatives.

Nationally, the Internal Revenue Service (IRS) began recalling its employees in June. In the D.C. area, some Defense Department workers have been called back, according to The Washington Post.

The American Federation of Government Employees (AFGE), the nation’s largest union of federal employees, sent a letter to OMB in April outlining six conditions employers must meet before workers can be required to return to the office. They include universal testing for COVID-19 and requirements that symptomatic employees be sent home on leave.

The union’s president, Everett Kelly, told WAMU last month that all agencies should be required to follow the same reopening procedures.

“You’ve got some agencies not making sure that employees returning back to work are tested,” Kelly said. “Some are making sure there’s adequate PPE. Some don’t take that to mean anything. That’s a very serious problem for us.”