Chris Hughes, the Facebook co-founder who purchased The New Republic less than four years ago and served as its publisher and editor-in-chief, has put the magazine up for sale.

In a memo to staff posted on blog-publishing platform Medium, Hughes, who claimed he had invested $20 million in the crisis-stricken progressive magazine, admitted that he had "underestimated the difficulty of transitioning an old and traditional institution into a digital media company in today’s quickly evolving climate."

"The unanswered question for The New Republic remains: can it find a sustainable business model that will power its journalism in the decades to come?" Hughes wrote. "Over the coming weeks, I’ll pursue conversations with those interested in taking on the mantle and supporting the next era of this institution. My aim is to place The New Republic in the hands of the most promising and dedicated potential steward."

Hughes bought the century-old magazine in March 2012 from a group of investors for an undisclosed amount. Those investors had bought the magazine from CanWest subsidiary CanWest Media Works International in 2007. The liberal mainstay publication, which was founded in 1914, currently has a print circulation of less than 50,000.

News of the publication's sale follows a turbulent period under the ownership of billionaire Hughes. After purchasing The New Republic, Hughes opened a new office in New York, cut down on the magazine’s editorials, increased cultural news items and bolstered its online presence, with plans to revamp the publication as a digital media company. In 2014 he replaced key newsroom staff, ousting then-editor Frank Foer, who was replaced by former Gawker editor Gabriel Snyder, brought in former Yahoo! News general manager Guy Vidra as CEO and reduced production to ten issues a year. Those events caused ten contributing editors to resign in protest, and print publication was briefly suspended.

Writing on the debacle in December 2014, Washington Post columnist Dana Milbank called Hughes "a dilettante and a fraud," and "a callow man who accidentally became rich … because he had the luck of being Facebook founder Mark Zuckerberg’s roommate."