In meetings and conversations over the past month, senior officials from the White House Covid-19 task force and the Food and Drug Administration have repeatedly accused CDC of withholding critical data needed to develop the booster shot plan — delaying work on the next step of President Joe Biden’s vaccination campaign and making it more difficult to set clear expectations for the public.

One particularly frustrating episode occurred last month, two officials said, when the agency appeared to publicly reject the administration’s plan to offer boosters to all adults. CDC Director Rochelle Walensky had joined other top Biden health officials in signing a high-profile statement on Aug. 18 endorsing the approach. But less than two weeks later, when it came time for CDC to make the case for boosters to an influential advisory panel, senior agency officials argued that priority should be given to nursing-home residents and frontline health workers before expanding access to other groups based on their vulnerability.

The new approach blindsided senior health officials across the federal government, further straining the tenuous relationship between the White House and the CDC.