The 59-year-old preacher, pundit and lightning rod for Tea Party fury is now more circumspect than some of his peers.
"One would be naive to say there were not some motivated by that [race]," Sharpton said.
He did note that the shutdown's impact has fallen disproportionately on minorities, since nonwhites comprise 34 percent of the federal labor force, slightly higher than the overall workforce, according to 2011 statistics.
Circumspection is something that's grown over time for Sharpton, whose explosive and ultimately unfounded allegations in New York's Tawana Brawley case in the late 1980s have long clouded the highlights of a career that included his own long-shot bid for the White House in 2004.
The Rejected Stone is Sharpton's third book, but by far his most personal. In it he expresses remorse over promoting Brawley's false rape allegations and admits to some "painful mistakes" - but he now believes that what he learned in that journey can help others.
"It's a story of redemption and it's a story of self-definition and allowing yourself to believe in yourself," he said yesterday.
Today, Sharpton will discuss the book at the Free Library of Philadelphia at noon (ticket including the book is $25) - with a promised appearance by Mayor Nutter - and he is slated to receive a proclamation from City Council member Kenyatta Johnson at City Hall.
He was in town just last month to rally parents, students and teachers protesting the Philadelphia school budget crisis.
It wasn't long ago that Sharpton teamed up with conservative former House Speaker Newt Gingrich to promote reforms that leaned heavily on charter schools - but he now says he wants to make clear that he doesn't back charters at the expense of traditional public schools.
"When we started with charter schools, many of them were church-sponsored and they had the freedom to do certain things and innovate - that's not what we're talking about," Sharpton said. "We're talking about people who really want to gut the public school system and privatize it - I'm opposed to that."
On Twitter: @Will_Bunch