SIOUX FALLS, S.D. — Big meatpacking companies that have struggled to keep plants running during the coronavirus crisis said Wednesday that they welcomed President Donald Trump’s executive order requiring them to stay open, but unions, some employees and Democrats questioned whether workers could be kept safe.

Trump used the Defense Production Act to classify meat processors as critical infrastructure to prevent supermarket shelves from running out of chicken, pork and other meat. Meatpacking plants across the country have closed as COVID-19 infections spread rapidly between workers, who often stand shoulder to shoulder on production lines.

Trump, who consulted with industry leaders before issuing the order, said it would relieve “bottlenecks” that the largest companies faced after workers fell ill and some died.

“They are so thrilled,” Trump said Wednesday after getting off a call with meatpacking executives. “They’re so happy. They’re all gung-ho, and we solved their problems.”

The executive order was widely seen as giving processors protection from liability for workers who become sick on the job. It came soon after a lawsuit accused Smithfield Foods of not doing enough to protect employees at its plant in Milan, Missouri. A federal judge in that case ordered Smithfield to follow federal recommendations.

The United Food and Commercial Workers union said it would appeal to governors for help, asking them to enforce rules that workers be kept 6 feet apart and that employees be provided with N95 masks and virus testing.

“Does it make sense to have meat in the markets if it takes the blood of the people who are dying to make it every day?” asked Menbere Tsegay, a worker at the Smithfield Foods plant in South Dakota, where more than 800 workers have confirmed cases of COVID-19. Two people have died, and the plant has been shut down since mid-April.

The threat of the virus has caused workers like Tsegay, a 35-year-old single mother of four children, to weigh whether to risk their health by working.

“I’d rather starve and wait this out than go back to work,” she said.

Companies have already sought changes to reduce risks by providing personal protective equipment, installing plexiglass shields between workers and reducing congestion by staggering shift start times, among other reforms.

The union said plexiglass barriers should not be used as a substitute for putting workers at a safe distance from one another. Union officials also want to slow down meat processing, including getting rid of waivers that allow plants to operate at faster speeds.

Smithfield Foods, which is working on a plan to reopen the Sioux Falls plant, said in a statement welcoming Trump’s order that it should make for easier access to protective equipment and testing for employees.