WASHINGTON — House Speaker Nancy Pelosi, D-Calif., implored President Donald Trump on Thursday to use his authority to force the mass production of critical supplies that the U.S. is lacking in the fight against the coronavirus.

“The president must immediately use the powers of the Defense Production Act to mass-produce and coordinate distribution of these critical supplies before the need worsens and the shortages become even more dire,” Pelosi said in a statement from her district in San Francisco.

Pelosi emphasized that the federal government can’t afford to waste time in addressing “shortages of critical medical and personal protective equipment” that she said is endangering health care workers.

“There is not a day to lose,” Pelosi said. “We must put more testing, more protective equipment and more ventilators into the hands of our front-line workers immediately.”

Pelosi’s statement came after Trump tweeted Wednesday evening that he had signed the Defense Production Act so he could use it in a “worst case scenario.”

“I only signed the Defense Production Act to combat the Chinese Virus should we need to invoke it in a worst case scenario in the future. Hopefully there will be no need, but we are all in this TOGETHER!” the president wrote.

Asked on Wednesday why he had waited to invoke the law, Trump said hospitals are “supposed to have ventilators” and the U.S. already has thousands of them, which he said “sounds like a lot.” But “nobody ever saw numbers like this, even with regard to testing,” he said. In response to a follow-up question, Trump said, “We are ordering thousands and thousands of ventilators.”

In her statement Thursday, Pelosi noted that 57 Democrats had called on Trump in a letter last Friday to invoke the Defense Production Act, warning that “the need for supplies to properly address the pandemic is acute.”