President Donald Trump is expected to sign an executive order Tuesday prioritizing the shipment of COVID-19 vaccines to Americans before other countries.

The news comes after the New York Times reported that the president declined a deal to purchase additional doses of the vaccine.

The federal government has secured 100 million doses of the Pfizer vaccine, which is set to be approved by the Federal Drug Administration later this week.

President Trump's refusal to secure more doses of the vaccine could delay the delivery of a second batch of doses for Americans. There's also concern that Pfizer would be unable to fulfill additional U.S. orders until June because the company is now committed to supplying the vaccine for other countries.

The 100 million doses are only enough to vaccinate 50 million people in the U.S. with two doses each. That's only 15% of the population.

Dr. Anthony Fauci says vaccinating only half the population may not be enough.