(Bloomberg) -- AstraZeneca Plc has begun stockpiling its Covid-19 vaccine for use in the U.S., providing a potential supply boost that could speed up President Joe Biden’s inoculation timetable, should the company win regulatory authorization.

A company executive said this week it has begun production and expects to have 30 million doses ready for U.S. distribution, once it’s approved by the U.S. Food and Drug Administration. AstraZeneca hasn’t yet applied to the FDA and hasn’t said when it will, but the U.K.-based company expects to produce 15 to 25 million doses per month for the U.S. after that.

If the FDA gives the green light, “we are expecting to start with 30 million,” Ruud Dobber, AstraZeneca’s executive vice president and president of its biopharmaceuticals unit, told CNBC this week. “We’re already producing at high speed as we speak, so we feel comfortable.”

The company is “on track” to eventually deliver a total of 300 million doses to the U.S., he said.

Meanwhile, Biden administration officials, speaking on condition of anonymity, said they’re aware the stockpile is accumulating but declined to say how big it is.

U.S. President Joe Biden announced this week that the U.S. would receive enough doses for nearly 300 million people, or enough for every American adult, by the end of May, a figure that includes the three authorized U.S. vaccines: from the Pfizer Inc.-BioNTech SE partnership, Moderna Inc. and Johnson & Johnson.

Biden’s White House has regularly said it doesn’t make plans or sketch out timelines that rely on potential future authorization of any one vaccine, instead treating new authorizations as something of a bonus. Its public time lines rely only on shipment projections for authorized vaccines.

If the AstraZeneca stockpile languishes, it could fuel tensions over vaccine availability. Italy this week blocked a shipment of AstraZeneca’s vaccines to Australia. As some countries -- chiefly the U.S., which has administered more doses than any country -- ramp up their inoculation programs, others are struggling with supply shortages.

Biden has made Covid response a cornerstone of his early administration, and has steadily announced increases in shipments.

The U.S. has ordered 300 million shots each from Moderna and Pfizer, each of which use two doses, providing enough for 300 million people. The U.S. has also ordered 100 million doses of J&J’s one-dose vaccine.

Even without AstraZeneca, the U.S. has firm orders for more doses than it has people, and far more than are eligible to get shots, which aren’t yet approved for people under age 16. The White House has declined to say when, or how, it would share any surplus doses with other nations, and rebuffed a request this week from Mexico’s president to do so.

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