“You don’t think Bernie Sanders is Barack Obama?,” NBC’s Andrea Mitchell asked Bill Clinton in New Hampshire on Tuesday. Responding to the query about whether the senator from Vermont’s loss but good showing in the Iowa caucuses was a repeat of then-Sen. Obama’s 2008 victory there, the former president was emphatic. “No,” he snipped before making his case. The former president is absolutely right.

Sanders is not like the man who upended the presumed coronation of then-New York Sen. Hillary Clinton eight years ago. Sure, Sanders is a fundraising juggernaut insurgent who inspires young people with talk of a political revolution. But Sanders lacks the one thing that will take him from maybe-sorta to “Yes, he can” overnight: a light-switch moment.

Jan. 3, 2008, in Iowa was that light-switch moment for Obama. That the overwhelmingly white Hawkeye State handed a decisive victory to an African American instead of to the better-known and seemingly inevitable Clinton was like a Bat Signal to black voters everywhere: He has  a shot, y’all! And like that, Clinton’s bond with African Americans — her husband was deemed then “the first black president,” remember? — was broken.

“Black support helps Clinton extend lead” was the headline on an October 2007 CNN article heralding her 57 percent to 33 percent. But her 24-point lead among African Americans became a 28-point deficit almost immediately after the Jan. 3, 2008, Iowa caucuses. In a CNN survey released two weeks later, Clinton’s black support fell to 31 percent, as Obama’s jumped to 59 percent, and never recovered.

The chances of a similarly dramatic pendulum swing for Sanders are slim to none. The cultural and historic significance of Obama’s ascendancy was humorously described by writer Trey Ellis in an August 2007 piece for the Huffington Post. “If there is even chance that there will be a black President in my life time I’ll be damned if I won’t be one of the millions out there that helped row that boat,” the Columbia University associate professor wrote. “For black folks, an Obama presidency would be as miraculously uplifting as sending a man to the moon.”

Obama became the nation’s first African American president with 95 percent of the black vote in 2008 and was reelected with 93 percent of it in 2012. The weekly tally conducted by Gallup puts his job approval rating among African Americans at 87 percent for the week ending on Jan. 31.

Clinton holds a commanding lead in net favorability over Sanders with black voters. According to Gallup, there is a 42-percentage-point spread between Clinton (78 percent) and Sanders (36 percent). To hold onto it, the former secretary of state is letting no daylight come between her and the president. By doing so, Clinton is not only drawing distinctions with Sanders, but she is also being as loyal to Obama as the black community is. If Sanders has any hope of prying a significant chunk of the black vote from Clinton, he must do it in South Carolina. And that’s a tall order.

African Americans make up 28 percent of the population there. But they “can make up over 50% of the Democratic Presidential Primary vote,” Winthrop University polling director Scott Huffmon said in a statement in November releasing the latest poll of likely Democratic primary voters. And to add to Sanders’s hurdle, Huffmon said that while “seventy-one percent of those surveyed said they were leaning toward voting for [Clinton],” that percentage was 80 percent for African Americans. The RealClearPolitics average currently puts Clinton’s lead over Sanders in the Palmetto State at 29.5 percentage points.

Sanders and his supporters say that his African American support will increase once African Americans get to know him. And that may be. But for many, his embrace of Cornel West, an Obama supporter turned petulant and petty Obama critic, is a red flag. For others, it’s his inability to talk about issues of race outside of the confines of class and poverty. And then some others might look askance at Sanders’s persistent talk in 2011 about the need for the incumbent president to face a primary challenge.

The only person as revered by the black community as Obama and the first lady is Eric Holder. The nation’s first African American attorney general endorsed Clinton last month and the campaign released a video Wednesday restating that fact. “If you want to make sure Republicans don’t take us backward,” Holder says,”help Hillary move us forward.” In a statement last month when he first endorsed her, Holder said, “Our next president can’t shy away from building on the progress of President Obama, which is why Hillary Clinton is the candidate that we need in the White House.”

As Steve Phillips writes in his new book, “Brown Is the New White: How the Demographic Revolution Has Created a New American Majority,” Obama showed that “successful candidacies require a large and enthusiastic Black vote.” Right now, I’m not seeing how Sanders does that in South Carolina and other states with large black voting blocs to get the nomination. For many African Americans, it will not be enough to have elected the nation’s first black president. The “millions out there that helped row that boat,” as Ellis wrote, will want to protect his legacy.

Follow Jonathan on Twitter: @Capehartj