Critics have said Mr. Zients, who made a fortune building two consultancies and taking them public, was an odd pick to run the pandemic response given his lack of experience in public health. But his past work touched on health care, both as the chief executive of the Advisory Board Company, a health care consultancy, and in the Obama administration, where he ran the effort to fix the healthcare.gov website.
During the surge of cases — and deaths — this winter, some blamed Mr. Zients for failing to do enough to prevent them, particularly when the highly transmissible Omicron variant caught the administration unprepared. Some supporters of Mr. Biden — particularly those on the Democratic left — were openly disdainful of both Mr. Zients and Ron Klain, the White House chief of staff.
“We wanted this to be run as a scientific operation; it’s being run as a management consultancy,” Gregg Gonsalves, an epidemiologist at Yale University who has often been critical of the administration, said in an interview in January. “Ron Klain and Jeff Zients are the wrong people to be where the buck stops on this.”
In January, The American Prospect, a liberal website, published an article titled “Fire Jeff Zients” that said he had “proven himself not up to the task, and Biden should relieve him of his duties.”
Mr. Zients was not always able to see around corners. In June, he declared that the nation was “entering a summer of joy, a summer of freedom,” not long after the Delta variant hammered India, and as it hit Britain. When it took hold in the United States over the summer, cases and deaths skyrocketed.
Critics pointed to the White House’s failure to ensure enough supply to meet the huge demand for mass rapid testing in the weeks before and after Christmas, a logistics problem that lingered well into January, as the Omicron surge began receding.
Dr. Fauci, though, defended Mr. Zients, saying his predictions last summer were based on the assumptions — incorrect, as it turned out — that 70 percent of the adult population would be vaccinated by July 4, and that the coronavirus could not spread among vaccinated people.