WASHINGTON — President Trump’s refusal to invoke the Defense Production Act to commandeer resources for the federal government is based on a bet that he can cajole the nation’s biggest manufacturers and tech firms to come together in a market-driven, if chaotic, consortium that will deliver critical equipment — from masks to ventilators — in time to abate a national crisis.

Over the past five days, after weeks of minimizing the virus and dismissing calls to organize a national response, administration officials have been pulling executives into the White House Situation Room, and connecting them by phone, in a desperate effort to unlock existing supplies and ramp up new production.

Rear Adm. John Polowczyk has been plucked from the staff of the Joint Chiefs, where he is a senior officer for military logistics, to run the effort to build a supply chain. And Peter Navarro, the White House trade adviser, is also playing a leading role. The government has essentially thrown out its existing playbook for dealing with pandemics, seizing the issue from the Department of Health and Human Services and moving it to the Federal Emergency Management Agency.

But it is far from clear that the effort to enlist companies like General Motors, Apple and Hanes, just a few of the firms that have promised to free up existing supplies of masks or repurpose 3-D printers to produce ventilator parts, constitutes an effective strategy.