Democratic lawmakers lambasted the nation’s workplace safety regulator Thursday during a House hearing, accusing the agency of failing to hold employers accountable while tens of thousands of essential workers fell ill during the coronavirus pandemic.

Rep. Alma Adams (D-N.C.), chairwoman of the House Education and Labor subcommittee on workforce protections, said the Occupational Safety and Health Administration has been “invisible” during what she called the worst worker-safety crisis of the agency’s 50-year history.

OSHA has “failed to develop the necessary tools it needs to combat this pandemic, and it has failed to fully use the tools it has,” Adams said in opening remarks.

Despite well-documented outbreaks among health-care, meat-processing, nursing home and retail workers, OSHA has issued only voluntary guidance on coronavirus mitigation, resisting calls from lawmakers and labor advocates to mandate social distancing and other protocols recommended by public heath professionals. OSHA is facing a lawsuit from the AFL-CIO, the nation’s largest federation of unions, which is seeking to compel the agency to issue an enforceable emergency temporary standard.

Loren Sweatt, principal deputy assistant secretary of labor for occupational safety and health, declined to answer questions during the hearing about an emergency temporary standard, citing the lawsuit. She also declined to respond to more generalized questions, such as whether the pandemic presented a “grave danger” for workers.

Republican lawmakers and top-ranking OSHA officials contend that the agency’s approach allows for flexibility and responsiveness in a fast-changing pandemic environment and that an emergency temporary standard would not better protect workers. The agency has provided guidance for retail, construction, meatpacking, restaurant and package delivery businesses, they say, because industry-specific guidelines are more effective than a single standard.

“A standard at this point would be an unproductive burden for businesses already struggling to reopen, potentially exposing them to unnecessary liability risks,” said Rep. Bradley Byrne (R-Ala.).

As of May 21, OSHA had received 4,268 coronavirus-related complaints, of which nearly 3,000 have already been closed, Sweatt said. She said that worker safety has been the agency’s “top priority” during the pandemic and that it will increase in-person inspections and enforcement of workplace coronavirus case reporting as states reopen.

“OSHA will not use guidance as a substitute for enforcement — rather, the agency has the tools and intent to pursue both avenues,” Sweatt said in opening remarks.

Though OSHA’s attempts to implement an infectious-disease standard have languished since the early days of the Trump administration, the general-duty clause of the Occupational Safety and Health Act of 1970 requires employers to provide a workplace “free of recognized hazards.” Sweatt and Labor Secretary Eugene Scalia have argued that existing regulations give the agency enough latitude to protect workers. But the agency has yet to issue a single pandemic citation under the general-duty clause.

Lawmakers on both sides of the aisle cited coronavirus outbreaks in meatpacking plants as indicative of the challenges companies and front-line workers are facing in the pandemic. Meat plants are fast-paced, demanding work environments where employees labor shoulder to shoulder, making social distancing a challenge. Low temperatures in plants, essential for food safety, can contribute to the virus’s spread.

OSHA and the Centers for Disease Control and Prevention issued specific industry guidance for meatpacking companies in late April as dozens of plants across the country were forced to close because of outbreaks. But this guidance is voluntary, and OSHA has said it does not intend to cite workplaces if they have made “good faith efforts” to comply.

As of Thursday, infections tied to meat plants had surpassed 18,500 and worker deaths were approaching 70, according to the Midwest Center for Investigative Reporting, which is tracking industry outbreaks through local news reports. Grocery workers have been similarly hit hard, with more than 5,500 testing positive for the coronavirus and more than 100 dying of covid-19, the disease the virus causes, The Washington Post has reported. Front-line health-care workers have gotten sick in even greater numbers, with more than 60,000 infected and more than 300 dying of covid-19, according to new CDC data.

Sweatt said OSHA has been actively working with stakeholders to monitor conditions in meat plants, including having daily conversations with the Agriculture Department’s Food Safety and Inspection Service. The agency is dealing with 58 “meatpacking enforcement activities,” Sweatt said, including 10 in-person physical inspections in the past week.

“The agency is doing everything we can related to this specific industry,” Sweatt said.

Correction: An earlier version of this story incorrectly said the the Occupational Safety and Health Administration issued an emergency temporary standard for employers during the H1N1 outbreak in 2009. The agency did not issue such a standard at that time. This version has been corrected.