"Right now, as I see the numbers," Perna told Connecticut Democrat Richard Blumenthal, "I do think it is potentially possible."

Citing Trump's unilateral break last month with the World Health Organization, Blumenthal pressed Perna on whether he would commit to working with any nation that offers information or cooperation for developing a COVID-19 vaccine.

"I commit to working with all nations that we deem are friendly to our national security," Perna replied.

Hawaii Democrat Mazie Hirono wanted to know if that included China.

"Right now, for me," the general responded, "it does not."

Noting that billions of dollars in contracts had already been awarded to at least five private pharmaceutical firms with little oversight, Hirono asked Perna if he would commit to briefing Congress every two weeks on Operation Warp Speed.

"Senator, I will report as directed," Perna told her, a reply that Hirono dismissed as "not making a commitment."

Maine Independent Angus King wanted to know what the price of a vaccine developed with public funds but produced by private industry should be.

"We're in negotiations with each company to make sure that we are going to obtain the right price for the vaccine," Perna assured King. "I commit to you that I will personally be involved in those conversations, and that we will not be gouged."

The logistics expert also acknowledged that several pharmaceutical firms that have received funding through Operation Warp Speed have not yet begun clinical trials in the U.S.

"Trials will begin for us 9 July with Moderna," he said, "followed by AstraZeneca and then Johnson & Johnson throughout the months of July, August, September."

Perna said another part of the effort he's to lead is identifying therapeutics capable of treating COVID-19. "We have some very promising candidates," he added, "that could be available as early as October, November."

Perna told the committee he did not have the authority to invoke the Defense Production Act, which some senators suggested could be used to require production by U.S. firms of needed supplies. But he said he felt "100% certain" either Defense Secretary Mark Esper or Health and Human Services Secretary Alex Azar could take such an action if he asked for it.

Mississippi Republican Roger Wicker told Perna there might be a simpler way to get fast results in the hunt for a vaccine.

"I would just ask you not to rule out among your bag of tools some sort of prize competition," Wicker said, "to financially incentivize these competitors to get there when we need them to get there."

Perna, whose confirmation appears likely, did not push back.

"I fully agree with you, senator," he said, without elaborating on what such a prize should be.