Here's the Real Reason Hillary Clinton Has a Lock on the Democratic Nomination

Support from African-Americans is key, and her would-be challengers aren't doing much to win it.

Hillary Clinton is a near-lock for the Democratic nomination for many reasons, but among the most significant is that her challengers have minimal appeal to the party's base of African-American voters.

Clinton learned firsthand the importance of their support in 2008, when many of them abandoned her presidential campaign to get behind the first viable African-American presidential candidate.

This time, she should have little concern about that: Barack Obama can't run again, and the candidates who are running haven't done much to rally African-American support.

(RELATED: Obama, Emboldened, Addresses Race as Never Before)

Vermont Sen. Bernie Sanders, the challenger with the most momentum, represents a state that's 95 percent white, where Asian-Americans and multi-racial voters outnumber blacks. He's focused most of his campaign message on income inequality, constraining Wall Street excess, and campaign finance reform, while avoiding discussions on race relations, urban policing, or gun control. Only 25 percent of non-white Democratic voters said they'd even consider backing the senator's presidential bid, according to last month's NBC/Wall Street Journal survey.

Former Maryland Gov. Martin O'Malley, despite representing a state where nearly half of Democratic voters are black, has been unable to make inroads with his onetime political base. In fact, he drew some jeers when he returned to Baltimore in the wake of violent rioting that tore apart the city. As mayor, his tough-on-crime measures were popular with Maryland voters, but the no-tolerance approach alienated many African-American voters in the state's largest city. Even some of his base-pleasing accomplishments as governor—such as his early support for gay marriage—hold limited appeal with black voters. In a recent speech, he awkwardly compared his experience as a "minority white candidate" for mayor to the broader African-American experience.

(RELATED: Martin O'Malley: I Wish Baltimore Got Body Cameras for Cops When I Was Mayor)

Meanwhile, Clinton's other rival is more conservative than the entire Republican presidential field when it comes to the Confederate flag. Former Sen. Jim Webb, who was the Democrats' Senate majority-maker less than a decade ago, now finds himself badly out of step with his party on civil rights issues. On Facebook, he called for "mutual respect" when considering the Confederate flag in a way that "respects the complicated history of the Civil War." He will struggle to make inroads with minorities, given how out of step he is with an increasingly progressive Democratic base.

Polls in Iowa and New Hampshire may show Clinton with less-than-commanding leads over Sanders and everyone else, but take those results with a grain of salt; they don't mean much going forward. Iowa and New Hampshire have among the most homogeneous Democratic electorates in the country, demographically disconnected from the party's base in most other states.

(RELATED: There's Something About Sanders)

Even a best-case scenario for Clinton's challengers wouldn't yield any long-term success. If, say, Sanders carried New Hampshire, he'd immediately need to translate that momentum to South Carolina, where African-Americans make up a majority of the Democratic primary vote. It's almost impossible to see Sanders's support—what political analyst Michael Barone calls his "Birkenstock constituency"—translating down South. Meanwhile in Nevada, where immigration is the dominant issue among Democratic activists, Sanders's relative silence on the subject makes him a poor fit. (Sanders helped scuttle George W. Bush's efforts for comprehensive immigration reform in 2007, attacking the bipartisan legislation for driving down wages for working-class Americans.)

The biggest question is whether Clinton's unimpeded path to the nomination is a product of her political strength, or a sign that Democrats don't have any other candidates who can appeal to their diverse constituency. If a candidate with stronger appeal to minority voters challenged her, would he or she experience an Obama-style wave of support? Are Clinton's favorable ratings so solid because of her lack of competition, or is her political standing dissuading others from running against her? It's the political version of the chicken-and-egg argument.

The answer is crucial to her strategy in the general election, where she's seeking to recreate Obama's old coalition by trying to connect to every one of his core constituencies. If African-American enthusiasm for Clinton comes close to matching Obama's, then the base-first approach will pay dividends down the road. But if she's winning non-white voters in the primary by default—running against old white men with limited ties to the rising Democratic electorate—she could face a rude awakening next November.