Democratic presidential candidate Sen. Bernie Sanders (I-Vt.) speaks during his campaign event at Morehouse College, a historically black college in Atlanta, on Feb. 16. (John Amis/European Pressphoto Agency)

Harry Jaffe is the author of the new book “Why Bernie Sanders Matters” and a writer for Washingtonian magazine.

Organizing a protest against police violence in the black community, a curly-haired kid from Brooklyn found himself with a Chicago police officer’s finger in his face. “It’s outside agitators like you who’re screwing this city up,” the cop told him. “The races got along fine before you people came here.”

That young man was Bernie Sanders, and the confrontation took place in 1962, while Sanders was a University of Chicago student. In the following years, Sanders would lead sit-ins against housing discrimination and get arrested while marching for equal education.

Now, as the 2016 campaign for president bears down on the fractious states beyond Iowa and New England, Sanders — today a 74-year-old U.S. senator from Vermont and candidate for the Democratic nomination for president — needs to convince minority voters that black lives still matter as much to him as they did 50 years ago.

Can he attract African Americans, Latinos and other minorities nationwide? And does Sanders — an avowed democratic socialist — have the ability to do this while finding ways to win over white voters beyond the progressives fueling his surprising rise? In short, does the Sanders campaign have legs?

I recently spent a year researching Sanders’s life for my book “Why Bernie Sanders Matters,” and I’m convinced it would be a mistake to underestimate his political skills and stamina.

For starters, Sanders cut his political teeth running against established opponents who didn’t take him seriously. Sound familiar? In his first race for mayor of Burlington, Vt., in 1980, the five-term incumbent Democrat scoffed at the young socialist for dwelling on the Vietnam War and imperialism. Sanders won by 10 votes by bringing together low-income people, disaffected Democrats and municipal workers fed up with the city’s Democratic machine. The Democrats called it a fluke and vowed to unseat him two years later. Sanders won a second term, then two more.

In 1990, Sanders moved on to the House of Representatives . By the time he ran for his fourth term, in 1996, the Republican National Committee had him in its crosshairs. Coincidentally, current GOP presidential contender John Kasich, then House Budget Committee chairman, came to Vermont to campaign against him. Republicans sicced a private investigator on his ex-wife. Vermonters cried foul and sent Sanders back to Congress — four more times.

Which highlights another feature of Sanders’s repertoire: Attack ads seem to boomerang. Sanders has perfected a kind of political jujitsu whereby he turns his opponents’ aggression against them by declining to respond in kind. This worked in 2005, when Republican Richard Tarrant told voters “not a single business will move to Vermont” if Sanders won a Senate seat. Sanders ignored him and won 70 percent to 30 percent.

Sanders famously runs against “the establishment,” but make no mistake: He’s an established politician. Counting his first quixotic campaign for Senate in 1971, he’s run for office 20 times, including for mayor, governor, congressman and senator. For his presidential quest, he’s assembled a top-tier team that’s been with him for decades and augmented it with 2008 Obama campaign digital guru Scott Goodstein, who is helping Sanders raise millions online and through social media.

The senator has leveraged his represention of a rural state. “Bernie has built ties to farmers across the country,” says Dexter Randall, a seventh-generation dairy farmer in Vermont’s remote “Northeast Kingdom.” “He gets us. He speaks our language.” He gets veterans, too. After Sanders voted against a 1991 resolution supporting the Gulf War, veterans turned their backs on him at a Burlington event. Chagrined, he began catering to vets, and he’s found a way to straddle the fault line between questioning the military budget and supporting those who serve. The Veterans Affairs reform bill he crafted with Sen. John McCain (R-Ariz.) in 2014 strengthened this bond.

Sanders’s Democratic opponent, former secretary of state Hillary Clinton, has strongly criticized his record on guns, especially his vote against the Brady bill and for legislation shielding gun makers from lawsuits. But this issue, too, could be a hidden strength. Sanders explains that he respects gun owners because he represents a state where so many residents hunt. Might such a stance win him votes among the nation’s gun owners?

Finally, if you’ve paid any attention at all to the 2016 campaign, you’ve no doubt heard Sanders hammer away at his major themes: The top 1 percent has an inordinate amount of wealth, American democracy has become an oligarchy, the economy is rigged. It’s not a message that’s narrowly aimed at minorities, but it’s not hard to see how it might resonate with them all the same. Indeed, given recent reports of Sanders making headway with supposedly pro-Clinton Hispanic voters in Nevada, this may already be happening.

His longtime aide Phil Fiermonte calls it “the oligarchy speech,” and he’s been delivering it for decades. “The world has come around to see things like he does,” Fiermonte told me, “through the same lens.” Does “the world” include Nevada and South Carolina? How about Florida and Ohio?

That’s the skeptics’ biggest question. Pundits love to compare Sanders’s campaign to the failed efforts of stalwart liberals such as Howard Dean, George McGovern and Eugene McCarthy. They roll out Republican Barry Goldwater. But these are extraordinary times. A great many voters seem receptive to Sanders’s brand of political revolution. If he can calibrate the 1960s rhetoric to the moment, persuade minorities to join his fight and build on his connections with Middle American constituencies, his campaign could go much further than anyone — even Sanders himself — ever thought possible.