Bernie Sanders is not apologizing for his newfound wealth.

The presidential candidate told supporters in Gary, Indiana, on Saturday: “I didn't know that it was a crime to write a good book, which turned out to be a best-seller.”

Sanders has come into a new income bracket largely through sales of his 2016 book Our Revolution: A Future to Believe In, where the senator shares stories from his underdog 2016 presidential campaign.

The book details Sanders' “progressive economic, environmental, racial, and social justice agenda,” an agenda that has made the book's success—and Sanders profit off that success—a sticking point.

The criticism started when Sanders admitted that he is now a millionaire earlier this week, while announcing he plans to release a decade of his tax returns before April 15—after dragging his feet over their release. His campaign swiftly emphasized that his policy platform, which is highly critical of billionaires and corporations, has not changed as a result.

“My view has always been that we need a progressive tax system which demands that the wealthiest people in this country finally start paying their fair share of taxes,” Sanders said. “If I make a lot of money, you make a lot of money, that is what I believe.”

Sanders' campaign manager Faiz Shakir defended his candidate, reiterating that the new income has not diminished his commitment to fighting social inequality.

“The fact that he is somebody who has personally benefited from that opportunity is something that he feels should be a shared opportunity with everyone else,” Shakir told CNN. “He's made some money off a book. And I think that the opportunity that he has had is evaporating for so many others. He feels that strongly ... There's nothing about any of these tax returns or the money or anything that'll come out that'll change that fundamental fact one bit.”

This week, ThinkProgress, a progressive news website, alleged in a video that Sanders had recently started aiming his wealth criticism higher. The video argued that the senator was now directing his ire at billionaires— instead of his fellow millionaires.

Sanders' high-wire act of fighting for the underclasses while profiting off of that fight is nothing new to popular politicians. But the senator has nonetheless taken heat from many who otherwise support his cause.

“I don't apologize for writing a book that was number three on the New York Times best seller, translated into five or six languages and that's that,” Sanders said.