Who is Jeff Zients, Biden's new chief of staff 

President Joe Biden has named Jeff Zients, who previously oversaw the administration's coronavirus response, as the next White House chief of staff.

The current chief of staff, Ron Klain, is to step down after the State Of The Union address on 7 February.

The role is considered to be one of the most powerful jobs in the US government.

"I promised to make government work for the American people. That's what Jeff does," Mr Biden said in a statement.

The White House will hold an official transition event in the coming days.

Mr Zients' return to the White House comes at a crucial moment for the US president as his staff begin to turn their attention to a potential re-election campaign in 2024.

President Biden is also facing a special counsel investigation into the handling of classified documents found at his private office and at his home in Delaware.

He first joined the Biden administration when he was tasked with managing the Biden administration's response to the coronavirus pandemic, including the distribution of vaccines in 2021 - a logistical public-health effort of historic scope.

By the summer of 2021, more than two-thirds of Americans had received the first round of vaccinations against Covid-19.

The White House was criticised at times for its handling of the pandemic, particularly scarcity of inexpensive tests during the omicron variant surge during the winter of 2021-22. When Mr Zients left the White House in April 2022, however, Mr Biden sang his praises.

"Jeff put his decades of management experience to work formulating and executing on a plan to build the infrastructure we needed to deliver vaccines, tests, treatment, and masks to hundreds of millions of Americans.," the president said in a statement. "I will miss his counsel and I'm grateful for his service."

But his departure from the White House was short lived.

Mr Zients returned in the autumn to help the Biden administration handle personnel changes as it entered the second half of its first term. It turns out one of the biggest changes would be Zients himself taking over the chief of staff job.

Mr Zients' resume is extensive, although his time in government service is limited.

He spent most of his professional career as a management consultant. He served as chair of the Corporate Executive Board and ran the Advisory Board Group, which he would later help take public with a multi-million-dollar stock offering. He also founded Portfolio Logic, an investment management firm focusing on the healthcare and business-services sectors.

His first government job came during Barack Obama's presidency, when he served as deputy director of the White House budget office and director of the National Economic Council, an administration advisory group. He also helped the Obama administration fix problems with the rollout of the Obamacare insurance exchange system, including the chaotic launch of the programme's website.

Mr Zients reported his net worth at around $90m on government disclosure documents in March 2021, which would make him the wealthiest of Mr Biden's top-level appointments.

His ties to the corporate world, including a stint on Facebook's board of directors after leaving the Obama administration, has opened him up to criticism from some government watchdog groups.

"Americans are appalled by profiteering in healthcare - Jeff Zients has become astonishingly rich by profiteering in healthcare," said Revolving Door Project Executive Director Jeff Hauser in a statement. "Americans are aghast at how social media companies have built monopolies and violated privacy laws. Zients served on the Board of Directors of Facebook as it was defending itself against growing attacks from both political parties."

Mr Zients also helped the 2020 Biden presidential campaign with financial management and co-chaired the president-elect's transition team, which faced numerous additional obstacles because of Donald Trump's refusal to acknowledge defeat.

But to Washingtonians, the incoming chief-of-staff is also known for co-founding the locally beloved chain of bagel purveyors known as Call Your Mother, which boasts several colourful establishments around DC.

Kayla Epstein contributed to this report.