WASHINGTON — President Donald Trump celebrated the expected approval of the first U.S. vaccine for the coronavirus Tuesday as the White House worked to instill confidence in the massive distribution effort that will largely be executed by President-elect Joe Biden

“They say it’s somewhat of a miracle and I think that’s true,” he declared.

Trump led Tuesday’s White House event celebrating “Operation Warp Speed.”

However, Trump was also facing scrutiny Tuesday after failing to lock in a chance to buy millions of additional doses of Pfizer’s vaccine, which has been shown to be highly effective against COVID-19. That decision could delay the delivery of a second batch of doses until Pfizer fulfills other international contracts.