The Trump administration on Monday directed federal agencies to expand telework to their staffs outside the D.C. region as services to the public began to contract to limit the spread of the coronavirus.

Following Sunday’s guidance to offer work from home to as many of the 300,000 Washington-area federal employees as they could, the White House budget office told agencies to offer remote work to additional employees across the country in areas with significant virus outbreaks.

The expanded telework to clear out federal buildings came as the government began shifting to more of an emergency footing than it had to fight the pandemic. The Defense Department quickly found its computer networks overwhelmed by employees trying to connect to its servers from home through virtual private networks — and the loads were prompting cyberattacks, officials said Monday.

White House officials told agency leaders to make sure they were prepared to quickly scale back operations as employees either call in sick or are absent because they cannot work from home — or staffing face-to-face public services becomes too risky, according to administration officials with knowledge of these conversations.

The still-uneven telework policy led 26 Senate Democrats, led by Sen. Chris Van Hollen (Md.), to send a letter to President Trump on Monday urging him to issue an executive order directing agencies to make telework mandatory “to the maximum extent practicable.” The letter criticized the administration for creating anxiety in the workforce by leaving it up to individual managers to decide how to proceed. “Voluntary guidance is not enough — agencies need clear orders,” the senators wrote.

The Social Security Administration announced late Monday that its 1,250 field offices and 165 hearing offices across the country will close to the public starting Tuesday.

“This decision protects the population we serve — older Americans and people with underlying medical conditions — and our employees during the Coronavirus (COVID-19) pandemic,” the agency said in a news release.

It was unclear how long the offices would close. The agency said it would continue to provide “critical services” over the phone, including hearing appeals of disability applications.

The decision at Social Security followed the closing by the Interior Department of some iconic sites, among them the Washington Monument and the Statue of Liberty National Monument and Ellis Island. About 10 other parks closed over the weekend, including California’s Golden Gate National Recreation Area.

Some federal offices acted decisively Monday to send employees home to work if they had not done so last week. The Equal Employment Opportunity Commission, for example, announced that after an employee at its Washington headquarters showed symptoms of the coronavirus, it sent its Washington-area staff home. Field offices have already begun conducting intake of discrimination complaints over the phone.

General Services Administration Administrator Emily Murphy put the agency’s headquarters staff on mandatory telework through “at least” April 3, she told the staff.

But Murphy’s missive did not address whether telework would be available to thousands of employees who handle the government’s real estate portfolio outside Washington.

The Agriculture Department told Washington-area employees on Monday that they could telework until early April, after an employee at the agency’s headquarters tested positive for the virus. The department also told managers in Seattle, New York City and parts of California to come up with plans to “maximize telework” for employees who have agreements in place, according to a memo sent to employees.

It was another example that some agencies are moving faster than others to clear their offices.

At the Education Department, spokeswoman Liz Hill said there is “maximum flexibility” on telework. “So, we aren’t closing the building but everyone who doesn’t need to be in the office is being encouraged to work from home.”

The U.S. Forest Service had no plans as of Monday to shut its ranger district offices, which provide a vital service in rural areas. Instead, the public is being asked to answer “self-screening” questions before meeting with the staff to determine whether they may be at risk of carrying the virus or came into contact with someone who is sick.

Back in Washington, the Pentagon confronted technology breakdowns.

During an online town hall meeting on Monday hosted by Pentagon Chief Management Officer Lisa Hershman, senior defense leaders addressed the Defense Department’s decision to maximize teleworking by personnel who do not require access to classified systems, a step that appears to have at least initially stressed the department’s technology arrangements.

Speaking alongside other senior officials, Deputy Chief Information Officer Essye Miller said the department has seen more than a 200 percent increase in access to the department’s IT help desk over the past week as thousands of employees transition to remote work. Miller instructed personnel who are teleworking to avoid using streaming services such as Pandora and said YouTube would no longer be available. She also urged employees to avoid lapses in digital security, advising them, for example, to avoid using nongovernment chat platforms while the Pentagon seeks to roll out sanctioned ways for employees to communicate. The department is also seeking to acquire more devices to enable remote access to the Pentagon’s network.

In another possible sign of the challenges of moving much of the Pentagon’s work online, the town hall’s broadcast was marked by streaming problems for at least some employees.

The department has already put in place telework exceptions for employees who have young children or other people requiring care at home, but it is requiring personnel to take leave to care for those individuals.

Laura Meckler contributed to this report.