WASHINGTON (AP) — President Joe Biden announced Jeff Zients as his next White House chief of staff on Friday, tapping an experienced technocrat who headed his administration’s response to the COVID-19 pandemic as Biden prepares for a reelection bid while facing an onslaught of investigations from a newly empowered House Republican majority.

Zients succeeds Ron Klain, a longtime fixture in Biden’s political orbit who led the White House through its highs — passage of consequential legislation like the massive infrastructure bill and the Democrats’ climate, health care and tax law, as well as dozens of judges confirmed in the first two years — as well as its lows, such as the rocky withdrawal of U.S. troops from Afghanistan. The transition is the first major personnel change for an administration that has had minimal turnover at its highest ranks and throughout the Cabinet.

“I’m confident that Jeff will continue Ron’s example of smart, steady leadership, as we continue to work hard every day for the people we were sent here to serve,” Biden said in a statement, adding that Zients, like Klain, “understands what it means to lead a team” and “is as focused on getting things done.”

Zients, 56, will be tasked with shepherding White House operations at Biden’s pivotal two-year mark, when the Democratic administration shifts from ambitious legislating to implementing those policies and fending off Republican efforts to defang the achievements. Zients (pronounced ZY’-ents) is also charged with steering the White House at a time when it is struggling to contain the fallout from discoveries of classified documents at Biden’s home in Wilmington, Delaware, and at his former institute in Washington, which has triggered a special counsel investigation.

Klain, in his resignation letter to Biden, said it was the “right time” for a transition after the president’s “indisputably historic” first two years in office.

“The halfway point of your first term – with two successful years behind us, and key decisions on the next two years ahead — is the right time for this team to have fresh leadership,” he wrote. “I have served longer than eight of the last nine Chiefs of Staff, and have given this job my all; now it is time for someone else to take it on.”

Klain pledged to do whatever he could to help Biden seek reelection should he “choose to run” in 2024. Biden has said that he “intends” to campaign for another term, and his staff has begun preparations ahead of an expected formal announcement in the spring but has said that the president has not made a formal decision.

Biden said that he would host an event at the White House next week to thank Klain for his service and to welcome Zients to the role.

Zients, not known to be a political operative, is expected to focus on the task of governing as a separate circle of advisers take the lead on politics, such as senior adviser Anita Dunn and Jen O’Malley Dillon, a deputy chief of staff who managed Biden’s 2020 presidential campaign. Presidential counselor Steve Ricchetti, senior adviser Mike Donilon and deputy chief of staff Bruce Reed will continue in Biden’s inner circle, while Klain, a longtime Democratic operative, will continue to advise and be involved from the outside.

Through both the Obama and Biden administrations, Zients has been the go-to person for significant operational challenges — such as a nationwide coronavirus vaccination campaign — or to repair bureaucratic messes such as the glitches and crashes that marked the launch of HealthCare.gov in fall 2013.

Then-President Barack Obama also tapped Zients in 2009 to eliminate the backlog in applicants for the Cash for Clunkers program, which offered rebates to drivers who swapped old cars for fuel-efficient vehicles. Zients later took on a similar challenge to smooth sign-ups for an updated version of the GI Bill.

Zients was vice chairman of Biden’s transition after he won in November 2020 and served as director of the National Economic Council during the Obama administration and acting director of the Office of Management and Budget.

“I asked Jeff Zients to handle some of our toughest challenges and, without fail, his leadership proved invaluable,” Obama tweeted on Friday. “He led my economic team as we pushed our most progressive economic policies, and I know he’ll serve @POTUS and the American people well in this new role.”

As COVID-19 coordinator, Zients led the effort that administered more than 220 million vaccinations in Biden’s first 100 days, while shoring up the nation’s supply of therapeutics and tests and distributing them. Zients gradually shifted the administration from a so-called “wartime” effort that grappled with COVID-19 at its most severe levels, to a strategy that would allow people to resume some normalcy with a virus that is likely to be endemic.

Although Zients left the administration in April 2022, he quietly returned in recent months to ensure the remaining two years of Biden’s term would be adequately staffed, a prelude to his taking on the much broader managerial role.

Zients’ appointment continues the White House chief of staff job as among the most influential positions in the U.S. government only to have ever been filled by white men.

Senate Majority Leader Chuck Schumer, D-N.Y., said Biden’s first two years “would not have been nearly as successful without Ron Klain by the President’s side” and noted that he spoke with the outgoing chief of staff multiple times every day, knowing that his counsel and questions would be directly communicated to Biden.

“I’ve known Jeff for many years and cannot think of a better person to help smoothly implement the transformational legislation Congress passed,” Schumer said. “Jeff is the epitome of what an outstanding chief of staff should be. He’s organized, focused and deliberate, exactly the right person to lead the Biden administration and ensure the American people see and feel the benefits of these new laws.”

In the private sector, Zients served as top executive at the Advisory Board Co., a Washington consulting firm, and he maintains close relations with the business community. He’s worth between about $90 million and $400 million, according to the financial disclosure he filed when he entered the White House in 2021.

“I respect him enormously,” Sen. Mitt Romney, R-Utah, who spoke regularly with Zients during his stint as COVID-19 response coordinator, said this week. “He’s a very bright guy. I expect to be able to communicate with him.”

Yet those business ties have already spurred criticism of the Zients selection from some on the left, who have blasted the incoming chief of staff for his private-sector background. Progressives are anticipating a shift from Klain, who regularly tended to that ideological wing of the party and retained close ties with liberal lawmakers.

Zients was also an initial investor in Call Your Mother, a local bagel shop, although he divested his shares before joining the administration in 2021. He has also served as chairman of the Children’s National Hospital in Washington.

Copyright © The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.