(Bloomberg) — The Amazon.com Inc. executive who oversaw the company’s push into brick-and-mortar retail and development of the Kindle e-reader plans to leave early next year, the company confirmed on Friday.

Steve Kessel, one of Amazon’s longest-serving executives, told his team of the move in an internal email. His planned departure was reported earlier by technology news site GeekWire.

Dave Clark, who oversees Amazon’s massive logistics and delivery operation and the Prime membership program, will inherit leadership of Amazon units that currently report to Kessel.

That includes some of the company’s most high-profile projects, including the Amazon Go cashierless convenience stores, the quick-delivery Prime Now program and the Whole Foods Market chain Amazon purchased in 2017.

Clark, himself a longtime Amazon executive, is among the most outspoken of the company’s tight-knit group of executives, frequently taking to Twitter to tout milestones and push back against Amazon’s critics.

In a post on Friday, he called Steve “a great leader and even better person.”

Kessel said he would focus on community service and nonprofit work. An Amazon spokeswoman said he wasn’t planning to join another company after he leaves in January.

“It’s hard to leave something I’ve loved doing for so long, inventing alongside a fantastic group of people, but it’s a good time to make this change because of the teams and plans we have in place,” Kessel wrote in the email obtained by GeekWire.