U.S. Food and Drug Administration Commissioner Stephen Hahn denied a report Friday that claimed White House chief of staff Mark Meadows told him he should resign if the FDA did not approve Pfizer’s coronavirus vaccine by the end of the day.

The Washington Post reported that Meadows gave an ultimatum to Hahn during a phone call earlier in the day, urging swift approval of the vaccine after an outside panel endorsed it for mass distribution. In a statement, Hahn said the report was “untrue.”

“This is an untrue representation of the phone call with the Chief of Staff,” Hahn said in a statement. “The FDA was encouraged to continue working expeditiously on Pfizer-BioNTech’s EUA request. FDA is committed to issuing this authorization quickly, as we noted in our statement this morning.”

Meadows told Hahn to ensure the FDA had “all hands on deck” to work toward an approval of the vaccine, sources with knowledge of the situation told Fox News’ John Roberts. The sources said the idea that Meadows warned Hahn to approve the vaccine by Friday or resign was “not entirely true.”

The Pfizer-BioNTech coronavirus vaccine was 95% effective in trials and displayed no major side effects, according to company officials. An outside panel of infectious disease experts voted Thursday to endorse the vaccine, the final step before career FDA officials determine whether to approve an emergency use authorization.

President Trump publicly admonished Hahn in a tweet Friday morning in which he demanded that FDA fast-track the approval process.

“While my pushing the money drenched but heavily bureaucratic @US_FDA saved five years in the approval of NUMEROUS great new vaccines, it is still a big, old, slow turtle,” Trump tweeted. Get the dam vaccines out NOW, Dr. Hahn @SteveFDA. Stop playing games and start saving lives!!!”

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Vaccinations are expected to begin within hours of the FDA’s approval. The FDA is not required to follow the outside advisory panel’s recommendation, but it is expected to act on the endorsement.

In a statement earlier Friday, the FDA said it had informed Pfizer officials that it would “rapidly work toward finalization and issuance of an emergency use authorization” of the vaccine.