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House Speaker Nancy Pelosi, D-Calif., on Thursday urged President Trump to "immediately" wield his powers under the Defense Production Act to combat the coronavirus crisis, a day after he said he would invoke it but does not yet need to use the powers available to him.

“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,” the California Democrat said in a statement. “There is not a day to lose. We must put more testing, more protective equipment and more ventilators into the hands of our frontline workers immediately.”

TRUMP ANNOUNCES HE IS INVOKING DEFENSE PRODUCTION ACT TO FIGHT CORONAVIRUS

Trump announced Wednesday that he was invoking the act, saying it “can do a lot of good things if we need it.”

The act, which was first enacted in 1950 as a response to the Korean War and has since been re-invoked more than 50 times, would streamline production of medical supplies to help the country battle the coronavirus pandemic and require businesses to sign contracts or fulfill orders deemed necessary for national defense.

It’s part of an expansive effort to combat the coronavirus pandemic that has shut down most of daily life in the U.S. in recent weeks.

But he tweeted late Wednesday that he was only using it if deemed necessary "in a worst case scenario."

TRUMP INVOKES DEFENSE PRODUCTION ACT: WHAT IS IT?

“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,” he tweeted. “Hopefully there will be no need, but we are all in this TOGETHER!”

For Pelosi and other Democrats, that need is already there.

“Right now, shortages of critical medical and personal protective equipment are harming our ability to fight the coronavirus epidemic, endangering frontline workers and making it harder to care for those who fall ill,” she said.

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As of Thursday morning, the U.S. has 9,415 confirmed cases of the virus and 150 deaths.

Fox News' Andrew O'Reilly contributed to this report.