The growing media platform Substack is solidly liberal, with 81 of the 100 top-selling titles in the U.S. Politics category being "left-leaning or progressive," according to researcher Kyle Tharp. 

Tharp, who pens the "Chaotic Era" newsletter, explained that Twitter used to be "the go-to arena for Democratic strategists, elected officials, and a new class of liberal take-makers," but Elon Musk’s takeover of the platform has pushed "liberal thought leaders" away.  

Lefty influencers have searched for a new home and some have migrated to Bluesky or Threads, but Tharp believes "a winner appears to have emerged" in recent months. 

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"Newsletter platform Substack is having a moment, fueled largely by an influx of liberal-leaning political and media figures eager to share their takes. Online pundits and anti-Trump resistance leaders like Heather Cox Richardson, Dan Pfeiffer, Simon Rosenberg, Norm Eisen, Steve Schmidt, and Mary Trump have built sizable audiences by weighing in on the news of the day," Tharp wrote. 

"Democratic elected officials—including Gavin Newsom, Pete Buttigieg, and Chris Murphy—have launched their own publications on the platform, aiming to grow dedicated followings ahead of potential presidential bids," he continued. 

"Perhaps most notably for the media industry, mainstream journalists who have left legacy outlets are finding new freedom to share their political opinions more openly on Substack. Among them: Taylor Lorenz, Mehdi Hasan, Tara Palmeri, Jennifer Rubin, Don Lemon, Jim Acosta, Terry Moran, and Dan Rather," Tharp added.

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Moran, who was axed from ABC News this month after posting an anti-Trump rant on X, quickly joined Substack and used the platform to double down on his social media post that called Trump and White House aide Stephen Miller "world-class haters."

"This, while very hot, is an observation, a description that is accurate and true," Moran said.

He added later, "It was something that was in my heart and mind. And I would say I used very strong language, deliberately, because he, I felt [was]… spitting venom and lies into our debate, degrading our public discourse, debasing it and using the power of the White House and what he's been given to grind us down in that bile. And, that's very disturbing to me."

Tharp noted that "They’re building a new echo chamber of left-leaning or anti-Trump commentary" one newsletter at a time. He included a graphic of the Top 50 "bestsellers" in the U.S. Politics category, which reveals the overwhelming majority of political content being consumed on Substack is of the liberal variety. 

The company appears to be embracing the liberal audience, as Tharp noted that anti-Trump figures Michael Cohen, Joe Walsh and Don Lemon are being used in the company’s latest advertising campaign. He’s unsure if the platform will continue the momentum "or if it’s simply the latest stopover for Twitter refugees in search of an audience." 

"For now, Substack stands as a key town square for a certain segment of the left, reshaping how political narratives are distributed, debated, and consumed," Tharp wrote.

While Substack does feature a handful of prominent non-liberals, such as Bari Weiss, it bills itself as "a new media app that connects you with the creators, ideas, and communities you care about most."

"Here, you can discover world-class video, podcasts, and writing from a diverse set of creators who cover politics, pop culture, food, philosophy, tech, travel, and so much more," Substack’s website states. 

Fox News Digital's Hanna Panreck and Kristine Parks contributed to this report.