WASHINGTON (Nexstar) — The White House plans to start rolling out COVID-19 vaccine booster shots on Monday, but two federal health agencies are urging the administration to rethink its plan.

The U.S. Food and Drug Administration and the Centers for Disease Control and Prevention are meeting Friday to debate if there is enough proof a booster shot is safe, effective and necessary.

White House Press Secretary Jen Psaki says rollout won’t happen until those agencies give the green light.

“Based on their recommendation, we’re prepared to operationalize our plan,” Psaki said.

The FDA and CDC will specifically discuss a request by Pfizer to approve a third booster shot six months after the second dose. Dueling data submitted ahead of the meeting suggests not everyone is on the same page.

FDA staff say they have yet to verify some data to support the need for a third shot, saying, “There are known and unknown biases that can affect their reliability.”

“It’s a public health crisis everywhere in our country,” said U.S. Sen. Sherrod Brown (D-Ohio).

Brown says the top priority right now needs to be convincing many Americans to get the first dose.

“I think the effort aimed for everybody needs to be whatever we can do to get people vaccinated,” he said.

Still, the White House says it is ready to activate its booster plan as promised.