The coronavirus science the White House has claimed to always follow took a rapid turn on Friday, just in time for President Biden's State of the Union address.

Fox News co-host Bill Hemmer pressed White House press secretary Jen Psaki Thursday during an extensive interview on "America’s Newsroom," asking why the White House dropped its indoor mask mandate for vaccinated individuals ahead of the speech to a joint session of Congress.

"What changed in the science yesterday, Monday, as opposed to a week ago Monday?" asked Hemmer. 

"It wasn’t actually yesterday, Bill. What the CDC did is they put out guidance last Friday that identified recommendations depending on what the hospitalization rates are in your part of the country," Psaki said.

EDUCATION ACTIVISTS AGREE DEMOCRATS' CHANGE OF HEART ON MASK MANDATES IS BASED ON ‘POLITICAL SCIENCE’

Throughout the past year, Biden, Psaki, and top medical officials like Dr. Anthony Fauci and Centers for Disease Control Director Dr. Rochelle Walensky have relentlessly professed to adhere to "the science," particularly when it comes to advocating for masking indoors, including in schools.

At one point, Fauci even said that criticism of him amounted to attacking "science" itself.

Biden has often used the phrase in speeches to justify masking measures recommended by the government; as recently as last month, Psaki said people should ignore local rulings on masks in schools and continue to abide by CDC guidelines on students wearing them, noting "the science is changing."

A flood of Democratic-led states recently dropped their mask rules as polls show dire numbers for the party ahead of the November midterms.

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Now Biden, who is often seen wearing a mask outdoors by himself, will stroll on Tuesday into the House chamber in Congress maskless. 

Fox News' Nikolas Lanum contributed to this report.