Ford Motor and General Electric are teaming up to build tens of thousands of ventilators, the manufacturers announced Monday, the latest development in a massive effort to retool existing U.S. manufacturing and supply chain capabilities for the treatment of covid-19 patients.

Medical experts have warned of ventilator shortages in the fight against the novel coronavirus, as hospitals become overwhelmed with patients who require breathing assistance as a result of the illness that has sickened at least 143,000 and killed more than 2,400 in the United States.

On a conference call Monday, Ford and GE said they have a partnership to build a simplified version of an existing ventilator, estimating they can produce 50,000 in 100 days starting April 20. The companies would ramp up production to meet a target of 30,000 ventilators a month after that, they said.

Still, Ford said in a news release it expects to produce just 1,500 ventilators by the end of April, after the point when health experts say the surge in U.S. hospitals will be greatest and well below estimates of what will be needed during that surge. By July 4, Ford said, it expects to have produced 50,000.

General Motors is embarking on a similar effort to build ventilators with partner Ventec Life Systems. GM is turning to its supply chain and retooling its Kokomo, Ind., plant, company officials said Monday, and it plans to involve about a thousand workers in its push to begin shipping ventilators by the end of April.

Ford and GE said they are producing an FDA-approved ventilator patented by Airon, a medical device company. The companies expect to put out 7,200 ventilators a week at full production, assisted by 500 United Auto Workers-represented employees.

President Trump has invoked the Defense Production Act to compel General Motors to produce ventilators and separately implored GM and Ford to move as fast as possible to produce ventilators in a tweet last week.

White House Defense Production Act coordinator Peter Navarro said in a joint statement that Ford and GE are moving in “Trump time,” referring to the speed of production, to build the devices. “We salute that effort and look forward to the first ventilators rolling off the Michigan assembly line in record time."

Rory Gamble, international president of the United Auto Workers, compared the effort to the days of “Rosie the Riveter” and praised the union’s workers for their contribution. Ford said the 500 workers on the project volunteered, although they are still receiving their regular salaries. “We are working very closely with Ford to make sure that all CDC guidelines are followed and that we are exercising an abundance of caution inside the plant,” he said.

The ventilator designed by Airon is not the most expensive or complicated one on the market, Ford said. Rather, it is designed for simplicity and ease of setup, which could be useful in the makeshift ICUs and hospitals being set up in places like New York. Ford said in the release that it would meet the needs of most coronavirus patients who require help breathing.

Airon had produced three pNeuton Model A ventilators per day in a production facility in Melbourne, Fla., according to the release, highlighting the need for faster manufacturing.

Before moving production to Michigan on April 20, Ford will send a team to Florida to help Airon boost production at its own facility.

Aaron Gregg contributed to this report.