Clark, who left Amazon last summer after a starry two-decade career at the e-retailer after losing a bake-off to former Amazon Web Services chief Andy Jassy, joined Flexport in September of last year as co-CEO. A company press release from last summer announcing Clark’s appointment called him “one of the world’s best operators at scale,” while Flexport founder Ryan Petersen told Geekwire that Clark would “shepherd Flexport into the most exciting phase of our journey.” 

Now, however, it looks like Petersen will be leading the flock alone. “Founders have the right to change their minds,” Clark wrote on X (formerly Twitter) on Wednesday, adding that he had been brought in to “take the company to the next level” and deliver on a vision of disrupting the logistics industry. Instead, it’s a back-to-basics move, he suggested. 

“Today, Ryan and I discussed his desire to return to focusing on growth in the core freight business,” he said. “In light of that, I feel that he is best suited to lead the company in that direction. As such, I will be resigning from my position at Flexport.”

Freightwaves was first to report that Clark was fired—abruptly—by the company’s board. The Information further reported that Petersen and Robert Swan, a board member, told Clark on Wednesday that he could either resign or be fired the following day. Clark all but confirmed his termination to The Information, telling the news outlet that “Ryan felt he was the best person to lead the company forward, and I agreed with him.”

In a statement confirming the change of leadership, a company spokesperson told Fortune on Wednesday, “Ryan and the rest of the board thank Dave Clark for his leadership over the past year. Flexport has nothing further to share on this matter at this time.”

It’s the second high-profile departure for Clark, a veteran logistics executive who spent most of his career at Amazon, where he made his name and rose to lead its worldwide consumer business. A staunch defender of the company, Clark famously locked horns with progressive senator Bernie Sanders after the Vermont independent expressed support for a union drive at Amazon’s Bessemer, Ala., warehouse, including an in-person visit. (The workers ultimately rejected unionizing.) 

“I often say we are the Bernie Sanders of employers, but that’s not quite right because we actually deliver a progressive workplace for our constituents: a $15 minimum wage, health care from day one, career progression, and a safe and inclusive work environment,” Clark told Insider in 2021. 

“So if you want to hear about $15 an hour and health care, Senator Sanders will be speaking downtown. But if you would like to make at least $15 an hour and have good health care, Amazon is hiring,” he said.

Clark was also a vocal defender of Amazon on Twitter (now X), lashing out at politicians (and comedian John Oliver) who criticized the company. In 2020, when workers at an Amazon warehouse in Staten Island moved to unionize, Vice reported that Clark was involved in a failed campaign to smear one of the organizers, including by painting him as “not smart or articulate.”

At Amazon, Clark was often named as a possible successor to founder Jeff Bezos. But he was ultimately passed over for Andy Jassy, who had led Amazon’s cloud division before ascending to the top spot. Clark moved from Amazon’s Seattle headquarters to Houston the year before leaving, and upon his resignation told Forbes that he had “outgrown my joy a little bit” and was yearning for a stint as CEO at a smaller company. 

He could now be eyeing an even bigger scale of leadership: The Wall Street Journal reported that he is considering running for governor of Texas and has hired political consultants toward that goal. 

[This article has been updated with details of Clark’s departure, including multiple reports that his resignation was involuntary.]