Ron Klain, Joe Biden’s chief of staff, is reportedly set to step down from his position, in what will be the biggest change to the US president’s inner circle of advisors since he took office two years ago.

Klain will announce his departure in the coming weeks, according to the New York Times, after telling colleagues that he is ready to move on following a grueling period of successes and frustrations that stretch back to Biden’s successful 2020 election campaign.

“Two hard years,” Klain tweeted on Friday, marking the second anniversary of Biden’s inauguration. “So much to be done. But so much progress.”

The impending exit of Klain follows a period where the chief of staff worked to secure Biden’s legislative priorities, including the bipartisan infrastructure bill and last year’s inflation reduction act, which was achieved following 18 months of often torturous negotiations between the White House and lawmakers, most notably Senator Joe Manchin from West Virginia.

More recently, Biden has come under scrutiny for alleged improper handling of federal documents, as well as fresh pressure from Republicans in their new majority in the House of Representatives. The new chief of staff is expected to have to mount a defense of Biden’s victories so far, as well as oversee the lead-up to a likely re-election bid by the 80-year-old president.

Klain, who is 61, has a long record in Democratic political circles, having been involved in both of Bill Clinton’s presidential campaigns, acted as chief of staff to both Al Gore and then Biden when the men served as vice president previously. Klain, a lawyer by training, also oversaw the Obama administration’s response to an outbreak of Ebola in 2014.

He was named as Biden’s chief of staff just a few days after the 2020 election victory was secured.