Update March 6: With Bernie Sanders and Hillary Clinton debating Sunday night in Flint, we are re-upping the below post, which recalls how Clinton keyed on the crisis in Flint much much earlier than Sanders.

Update 8:42 p.m. Feb. 4: In a scoop delivered by The Post's Anne Gearan The Fix has learned that Clinton will visit Flint on Sunday. It is the latest example of Clinton emphasizing the crisis there in a way that Bernie Sanders simply has not.

(Relatedly, the DNC also announced this week that it would hold a debate in Flint on March 6.)

The below post was written after the last Democratic debate on Jan. 17, when Clinton was the first Democratic candidate to bring up Flint, unprompted, in a debate. As we wrote just today, Sanders continues to struggle when it comes to crafting a message that appeals to black voters.

Hillary Clinton and Bernie Sanders slammed Michigan Gov. Rick Snyder (R) over his handling of the Flint, Mich. water crisis. (NBC)

There's no way to say for sure what made Hillary Clinton turn to the crisis in Flint, Mich., when debate moderator Lester Holt asked each of the candidates to identify a big issue left untouched during Sunday night's Democratic presidential primary debate.

Here's the exchange:

CLINTON: I spent a lot of time last week being outraged by what's happening in Flint, Michigan, and I think every single American should be outraged. We've had a city in the United States of America where the population which is poor in many ways and majority African American has been drinking and bathing in lead-contaminated water. And the governor of that state acted as though he didn't really care.
He had a request for help and he had basically stone walled. I'll tell you what, if the kids in a rich suburb of Detroit had been drinking contaminated water and being bathed in it, there would've been action.
So I sent my top campaign aide down there to talk to the mayor of Flint to see what I could to help. I issued a statement about what we needed to do and then I went on a TV show and I said, "It was outrageous that the governor hadn't acted, and within two hours he had."
HOLT: And that's time.
CLINTON: I want to be a president who takes care of the big problems and the problems that are affecting the people of our country every day.

Clinton's motivation could be, as she put it, that she has been genuinely outraged by the public-water disaster unfolding in Flint, a predominantly black city where nearly 42 percent of the population also lives in poverty. Really, the situation in Flint is about as outrageous and dangerous as events created by public policy, regulation and spending decisions come.

There are about 8,000 children under the age of 5 in Flint who may have suffered permanent, life-altering brain damage because of the volume of lead in the city's water. And that is just a tally of the youngest children in Flint.

But that's not even the only reason for decent people across the political spectrum to be outraged by the situation in Flint. Lead did not leach into Flint's water supply because of some undetected leak or natural disaster. Potentially brain-damaging lead was delivered into the lives and bodies of Flint's roughly 99,000 residents via this entirely man-made combination: A decision to pull the public water supply from a cheaper source long understood to be polluted. That water included components so corrosive, that it then eroded the city's pipes. And, as a result, the liquid flowing out of some of Flint's taps actually meets the official definition of toxic waste.

Now it seems each day that new information emerges showing some local, state or federal official knew that there were serious problems with Flint's water long before sounding any kind of alarm.

Clinton might also have been propelled to mention Flint for reasons not directly connected to the incredible assault on human health and safety described above. Sen. Bernie Sanders — an independent from Vermont — is now beating her in Iowa.

Back in 2008 when the conventional wisdom leaned toward a Clinton victory in Iowa and Clinton as the eventual Democratic Party presidential nominee, a one-term black senator from Illinois who ran to Clinton's left beat her. That set off a chain of primaries that included some Clinton wins and some Clinton losses. That mix damaged the idea that Clinton was the inevitable, singularly electable nominee. Soon enough, Obama became the favorite.

Clinton knows that voters of color are a real weak spot in the Sanders coalition. She also knows that no Democrat can win without these voters. And no, Sanders supporters, simply insisting that voters of color will eventually see the Sanders light won't magically change the fact that most non-white Democrats are Clinton supporters. Those kinds of condescending claims have been made by camp Sanders for a long time. The results are clear. Just look at the chart above.  

Bringing up Flint gave Clinton an opportunity to emphasize to voters of color — limited as they are in Iowa and New Hampshire but much more prominent in the states that follow — that she does understand the ways that race and class continue to sometimes boldly, sometimes insidiously distort almost every aspect of American life. Clinton deployed her seemingly newfound comfort talking about structural racism in a political setting. Then, she pretty much elevated Flint and the specter of environmental racism to a presidential campaign issue.

Most likely, some combination of the two possibilities outlined above — genuine outrage and political goals — prompted Clinton to say what she did during the Sunday night debate.

Now, in fairness, Clinton might have mentioned Flint first and most forcefully during the debate. But, on Friday, two full days before the debate, it was Sanders who first publicly called for Michigan Gov. Rick Snyder (R) to resign. Then on Sunday, Sanders restated that call on the debate stage in stirring moral terms.

It produced one of Sanders's more memorable public statements: "A man who acts that irresponsibly should not be in power," Sanders said.

Sanders's call for Snyder's resignation is also an arguably bigger and riskier stance than privately dispatching a campaign aide or talking about Flint on television. And we did not miss the fact that Clinton seemed to describe dispatching and television talking — her own actions — as somehow essential in getting Snyder to declare the Flint situation an official emergency.

But step back just a bit and think about how Flint got to now. Then, this becomes clear: Every candidate on that stage Sunday night really let more than a few important opportunities pass. Each of them could have connected Flint to the core Democratic argument for the economic and social benefits of intensive infrastructure investment, urban and suburban revitalization and the importance of strong environmental regulation.

There were also political points to be scored by linking the Flint disaster to cost-cutting and conservatives' constant push to shrink government and spend less. And there was the chance to posit that Democratic Party ideals — such as government must protect people from certain things; that some level of suffering, indignity and injustice simply should not exist in the United States, and that the wealthy need to do more to shoulder public costs — amount to the best way to prevent problems like the ones in Flint.

Flint is far from the only American city where the disappearance of thousands of jobs paying middle-class wages to a racially diverse array of workers has wrought a devastating toll on the community. In the decades since General Motors pulled out of Flint, it left behind a population with less money, bigger social service demands and a severely reduced tax base to fund those services.

And Flint did what most similar cities have done. As crimes like murder and arson rose to national trend-setting levels, the city focused on cutting costs. That included, rather illogically, slashing the size of Flint's police and fire departments. As people who could left Flint in large numbers hoping to find work, safety or both, state officials seemed to settle into a routine of claims that Flint's profligacy or inefficiency were the city's real problem.

And that very conservative read on the situation in Flint often overshadowed conversations about human needs. Certainly, all of that played a role in getting Flint to 2011 when Snyder appointed an emergency manager to oversee the city's major financial (and as it turns out health and environmental) decisions.

To put things more plainly, Flint may well be the canary in a coal mine of corporate and government divestment from cities.

That general pattern — something that, in fairness, began long before Snyder took office in Michigan — has produced and fed massive economic, social and infrastructure decay in American cities.

You see, there was a big opportunity Sunday night that not one candidate took.

That opportunity: To sound a political alarm about the age and condition of water pipes and water treatment systems, roads, bridges, schools, and yes, even regulatory agencies around the country. The Democrat who did so could have recast Flint from a singular and horrific crisis to a place where many things currently being ignored or downplayed in cities across the country have become clear. These are things that may also be putting other Americans at grave risk.

On Sunday, Clinton came the closest to getting that done.

Update 6:58 a.m. Jan. 19: Clinton on Monday's Martin Luther King Jr. holiday reiterated her focus on the situation in Flint, saying, "We would be outraged if this happened to white kids, and we should be outraged that it's happening right now to black kids."

Clinton later called into Rachel Maddow's show to talk about it.