Crime novelist Don Winslow says he’s retiring from writing.

Winslow, known for bestselling novels such as The Cartel and The Force, made the announcement on Twitter, explaining that his last book will be published in 2024. That novel will be the third installment of a trilogy that begins with City on Fire, to be published Tuesday by William Morrow.

“I love writing and do not make this decision likely, but I’m going to pick a fight,” Winslow wrote. “Donald Trump was defeated in 2020, but Trumpism is a cancer that has metastasized across the country.”

Winslow explained that he’ll be dedicating his career to political activism, which he’s pursued in the past few years through a series of videos critical of Trump and his supporters, and tweets opposing Republican politicians.

“The Democratic Party has better ideas, better candidates, and a better vision for tomorrow,” Winslow wrote. “What they don’t have is better messaging and I’m going to try and change that. That will be my focus now.”

In an interview with Jeff Glor on CBS Mornings, Winslow acknowledged that his retirement from writing is “a big deal.”

“I’ve told the stories that I want to tell,” Winslow said. “And I don’t want to keep writing for the sake of publishing, or just for the sake of a paycheck. So I think now is the time.”

Michael Schaub is a Texas-based journalist and regular contributor to NPR.