Public health experts and former Biden transition advisers had also lobbied the White House in recent weeks to give out masks, arguing that cheap and genuine N95s are still difficult for people to find.

The administration plans to make the masks available at tens of thousands of pharmacies and health centers by early February, the White House official said, which people will then be able to pick up for free.

The supply will not include child-sized masks, though two people with knowledge of the matter said the government is working to procure them.

Still, it represents the most significant federal effort to distribute face coverings since the pandemic began. The Biden administration last year sent out more than 30 million masks to sites within high-risk communities, though those were cloth coverings.

This new initiative follows weeks of debate over whether the administration should step in to distribute masks, with some senior officials skeptical that giving out N95s would make a significant difference in slowing the spread.

Several states have already dropped their mask mandates, and in deep red areas hardest-hit by Covid-19, there’s little appetite for mask wearing and other preventive measures that have been heavily politicized throughout the pandemic.

The Centers for Disease Control and Prevention, meanwhile, has refused calls to change its guidance to recommend that everyone wear high-quality masks like N95s, rather than cloth coverings.

But with Omicron cases and hospitalizations hitting fresh highs, officials and outside public health officials who favored a new distribution program argued that the government should play a role in making the masks more readily accessible.

President Joe Biden previewed the plan last week, acknowledging at the time that for some individuals, obtaining high-quality masks is still “not always affordable or convenient.”

“I know we all wish that we could finally be done with wearing masks,” Biden said during a speech announcing a new effort to use the military to support hospitals. “I get it. But they’re a really important tool to stop the spread, especially of a highly transmittable Omicron variant.”

Biden is slated to hold a press conference later on Wednesday, where he’s expected to defend the administration’s efforts to tamp down the Omicron surge and tout the mask plan.

The 400 million masks represent a little more than half of the federal stockpile that officials have worked to replenish since the earliest days of the Covid-19 outbreak — when severe shortages forced frontline health workers to fashion their own personal protective equipment and re-wear masks for several days.

There are more than 750 million N95 masks in the Strategic National Stockpile, the White House official said, with ample supply for health providers and the public available for purchase.