Sen. Elizabeth Warren (D-MA), the one-time Democratic presidential hopeful, will ask President Donald Trump to deploy part of the military across the country to turn existing facilities into hospitals as part of the country’s response to the coronavirus pandemic.

Warren, a member of the Senate Armed Services Committee, will send a letter to the president with the request on Wednesday. In the letter, obtained by Vox before its release, she will insist that Trump direct the Army Corps of Engineers to retrofit existing buildings to care for Covid-19 patients.

“Given the reality of the exponential growth of the virus, supplemental infrastructure must be designated and ready to receive patients immediately,” the senator writes. “The Army Corps is in position to help address this public health emergency by converting existing space into temporary medical centers. Taking this action will save lives.”

“I urge you to direct the Secretary of Defense to activate the Army Corps in executing this mission nationwide,” she adds, noting that troops should support civilian leaders in their response efforts. She also said the Army Corps should assess current facilities that could be used for medical reasons in case of emergency.

When I asked the senator’s aide how the US should pay for those projects, the answer was that Warren “supports taking DoD military construction funds previously diverted for wall construction and diverting them to supplement the federal government’s coronavirus response.”

Defense Secretary Mark Esper seemed open to deploying the military team during a Tuesday press briefing, though said nothing of how to pay for their work.

“I’m more than willing to send the Army Corps of Engineers out to work with states and to see what we can provide, what we can offer,” he told reporters. “The Corps of Engineers is a contracting body that does program oversight and work, and if we can be useful, if we can help, certainly willing to provide that — that service.”

Hours later, Esper revealed on Fox News that the Army Corps will grant New York Gov. Andrew Cuomo’s request to work in the state and address its shortage of hospital beds. “I gave him my full commitment that we would get the Corps of Engineers up there soonest, to assess the problem and see how we can help out,” the secretary told Brett Baier.

Why the Army Corps could be useful in the coronavirus response

The Army Corps has done this kind of work before.

In 2014, members of them team were sent to Liberia as part of America’s Ebola outbreak response in West Africa. During their roughly six-month deployment, they built treatment units and helped with logistics like transport. It’s no surprise, then, that a growing chorus of experts want the Army Corps more involved in the US coronavirus effort.

There are two important things to know about that team, though. First, it usually takes its requests for complex projects — like building dams — from states, not the president. Second, a lot of what it does is manage, plan, and engineer projects, but it typically contracts out many of the actual building responsibilities to the private sector.

Brad Carson, the top Army personnel official from 2015 to 2016, told me that Trump can direct the Army Corps to do what he wants. “The president can ask them to build anything,” he said. “They are part of the US Army, and he’s commander in chief.” What’s more, he and others noted, there are ways to expedite the contracting process to begin to get needed materials and labor to start major projects now.

Some, though, say other military members can build what the senator is asking for without involving the Army Corps. “The regular Army and National Guard can also do a lot of this type of work. “It’s not like building big dams,” says Andrew Weber, the Pentagon’s top biological defense official from 2011 to 2014. “We need fast, uniformed personnel providing labor and leadership.”

Whether the Army Corps becomes involved or not, there are many in power who want more medical centers available to treat patients. And for the moment, it’s unclear if Trump is one of those people.