Hillary Clinton and Bernie Sanders faced off in Flint, Mich. on March 6. Here are the key moments. (Peter Stevenson/The Washington Post)

Hillary Clinton and Bernie Sanders faced off in Flint, Mich. on March 6. Here are the key moments. (Peter Stevenson/The Washington Post)

Sunday night’s Democratic presidential debate here focused heavily on the lead crisis in this majority African American city, as well as differences between the candidates on issues of trade, jobs, guns and fracking.

There were also points of agreement on policy – former secretary of state Hillary Clinton joined Sen. Bernie Sanders in his previous call for Michigan’s Republican governor to resign in the midst of Flint’s water crisis — and few mentions of the emerging GOP field, including front-runner Donald Trump.

“We have our differences and we get into vigorous debate about issue, but compare the substance of this debate with what you saw on the Republican stage last week,” Clinton said to applause.

Sanders chimed in: “When you watch these Republican debates, you know why we need to address the mental health.”

But throughout the night, Sanders remained unrelenting in attacking Clinton for her connections to Wall Street and her positions on past trade deals. Clinton criticized the Vermont senator for his position on gun manufacturer liability and investing in exports.

[Sanders keeps raising millions — and spending them, a potential problem for Clinton]

Much of Sunday night’s debate in Flint has been about points of contrast between the two Democratic candidates, including intricacies of gun control approaches and trade policies, while they also noted points of agreement, such as dismantling institutional racism.

Clinton has a clearer path to the Democratic nomination than Sanders and leads him by double-digit margins in Michigan polls.

Regarding fracking, Clinton offered what she cast as a measured approach which ultimately would result in few “places in America where fracking will be able to take place.”

But when Sanders was asked whether he supported fracking, he responded: “My answer is a lot shorter: No, I do not support fracking.”

In a Democratic primary contest in which African American voters will play a crucial role, Clinton and Sanders were both also asked about their racial blind spots by CNN’s Don Lemon, and about their support for a two-decades-old crime bill.

Both candidates noted that they had indeed voted for the 1994 crime bill, which has been blamed for furthering racial disparities in the criminal justice system, while emphasizing that they want to reform the criminal justice system. The 1994 bill also included provisions for harsher penalties regarding violence against women.

“I can’t pretend to have had the experience you’ve had,” Clinton told Lemon, “and that others have had, but I will do everything that I possibly can, to do the best I can, to not just understand and empathize but to tear down the barriers of systematic racism.”

Sanders echoed Clinton regarding racial blind spots, talking about his history in the Civil Rights Movement of the 1960s.

“We must be firm in making it clear that we will end institutional racism and reform a broken criminal justice system,” Sanders said.

[The Hillary Clinton-Bernie Sanders race is becoming very predictable]

The debate also covered the issue of guns, after the father of one of the victims of the Kalamazoo shooting rampage asked the candidates about what they would do to curb the tide of gun violence in America.

Clinton called for ending the gun show loophole, and criticized Sanders for his position against holding gun manufacturers legally liable following mass shootings.

“I voted against giving them immunity, but I think we should very seriously move to repeal that,” she said.

Sanders agreed on the need to expand background checks, but disagreed with holding manufacturers liable, unless “they understand that they’re selling guns into an area that it’s getting into the hands of criminals.”

Sanders also criticized Clinton for her past support of trade deals, and the former secretary of state opened a line of attack on Sanders for his opposition to the Export-Import Bank.

“I think we’re in a race for exports,” Clinton argued. “Here in Michigan, there’s been $11 billion in recent years used to support exports, primarily from small business. I favor it, he opposes it.”

Sanders, the lone member of the Democratic caucus in the Senate to oppose the Export-Import Bank, fired back, describing the Export-Import Bank as “the Bank of Boeing” and a source of money for major corporations.

“Democrats are not always right,” Sanders said. “Democrats have supported corporate welfare.”

Earlier in the debate, Sanders and Clinton sparred over trade and jobs, after questions turned from the Flint lead water crisis.

Sanders had hammered Clinton for her previous support of trade deals. She responded by laying out a series of proposals to create incentives for companies to invest and stay in the United States, and criticizing Sanders for voting against the auto bailout.

Sanders, responding that the vote was actually one against a Wall Street bailout, cut off Clinton: “Excuse me, I’m talking,” he said, prompting “oh’s” from the audience.

Clinton responded: “If you’re going to talk then tell the whole story.”

[Flint water crisis emerges as a key piece of Democrats’ election-year message]

The debate began with both candidates calling for Snyder’s resignation and describing Flint’s lead water crisis as an outrageous failure of governance.

It’s a call that Sanders has made previously and repeated Sunday night. Clinton joined him Sunday, saying Snyder should be recalled or should resign.

Clinton also said the state should use its “rainy day” fund to help residents in the city.

“It’s raining lead in Flint and the state is derelict for not coming forward to help,” Clinton said.

News that Sanders won the Maine Democratic caucus Sunday came as the two faced off in Flint. Sanders was expected to do well in Maine, and has already won other northeastern states, including his home state of Vermont and New Hampshire, while Clinton won in Massachusetts.

Sunday’s victory in Maine means he will win at least 14 delegates of Maine’s 25 pledged delegates, and Clinton will win at least six, according to the Associated Press.

Not including Maine’s delegates, Clinton has at least 1,123 total delegates, while Sanders has 484, including superdelegates. The race continues to 2,383, the number of delegates needed to win the Democratic nomination.

The debate, which began at 8 p.m. Eastern time and is being televised on CNN, was added to the Democrats’ schedule after Sanders emerged as a stronger-than-expected challenger. Clinton and Sanders are facing off here in Flint, which was chosen to highlight a two-year-old poisoned-water crisis that has paralyzed the majority-African American city.

Both candidates have campaigned hard in Michigan, which they consider a bellwether for the fall election. The state will serve as a test of Clinton’s institutional support from workers’ unions and of Sanders’s appeal with the working class.

Sanders drew a large crowd for a rally in Warren, Mich., on Saturday, while Clinton held a small session with African American ministers in Detroit before addressing state Democrats at a dinner.

Hours before Sunday’s debate began, Sanders called an impromptu news conference where he announced the endorsement of Flint native and former U.S. senator Don Riegle.

There, Sanders acknowledged that he trails Clinton in Michigan, in part because he has continued to struggle to reach African American voters, who represent about 14 percent of Michigan’s population.

“We started off way, way down here, and I think that gap is closing,” Sanders said at Sunday’s news conference. “The black vote in Michigan, the black vote all over the country, is enormously important,” he added.

But Sanders noted that he believes the divide has been greater along generational lines than along racial lines: “Our campaign is doing quite well with younger whites, younger African Americans and younger Latinos.”

Sunday night is the first time the candidates have debated since the Super Tuesday contests, when Clinton emerged with a lead of nearly 200 pledged delegates over Sanders. She slightly expanded her delegate lead after a crucial win in Louisiana on Saturday, while Sanders claimed victories in Nebraska and Kansas.

The Sanders campaign believes that the primary map becomes more favorable to their candidate as the race shifts out of the South, but his window to overtake Clinton is narrowing.

Top Sanders strategists tried to make the case last week that the self-described democratic socialist from Vermont still has a path to the Democratic nomination, which involves winning Michigan and other delegate-rich targets such as New York and California.

But Clinton’s advisers hope that by April, her delegate advantage will make it virtually impossible for Sanders to claim the nomination. And Clinton has already begun shifting her focus on the campaign trail to a potential general election matchup against the Republican front-runner, Donald J. Trump. In recent days, she has pitched supporters with warnings about the GOP field.

“We are the last line of defense against Trump succeeding President Obama as our 45th president, and we have got to be ready to fight him with every last thing we’ve got,” Clinton told supporters in a fundraising email.

Michigan holds its primary Tuesday and is the first of the delegate-rich industrial Midwest states to vote. Sanders views the state as winnable despite Clinton’s steady and comfortable lead in state polling.

A Detroit Free Press-WXYZ poll released late Saturday shows her leading Sanders 56 percent to 31 percent, a gap that “suggests it may be too late for him to battle back to a victory here despite a strong effort in recent days,” the newspaper wrote.

The Democratic candidates pounced on the Flint water crisis when it exploded in the public’s consciousness in January.

The crisis dates to April 2014, when the city, at the time under state oversight, changed its water source from Detroit’s system to the Flint River to save money. Corrosion-control additives were not added to the water supply, which allowed lead from aging pipes to leach into the water used by the people in Flint.

Complaints about the smell and taste of the water emerged almost immediately, but revelations emerged this year that the Michigan Department of Environmental Quality and other parts of Republican Gov. Rick Snyder’s administration dismissed those complaints. Both Clinton and Sanders have said that the crisis would never have happened in a richer, whiter city.

To Democrats, both in Michigan and nationally, the refusal to acknowledge the problem and the negligence that created it is emblematic of Republican-led government failure. That Flint is predominantly poor and black exacerbated a narrative about Republicans being less concerned about minorities.

[In Flint, Clinton casts herself as a problem-solver — and looks past N.H.]

Both Clinton and Sanders have made much of the Flint crisis. The former secretary of state was first, making contact with Flint’s mayor in January and incorporating references to the matter in virtually every speech since. Clinton first mentioned the Flint crisis during a debate with Sanders in South Carolina, where a majority of Democratic voters are black. She also left a losing campaign in New Hampshire for one day in February to hold a community meeting in Flint, and she and her daughter, Chelsea, returned again in February.

Sanders, who opened a campaign office in Flint, also has visited and has been running a television ad in recent weeks highlighting his dismay at the situation.

[Sanders visits Flint, says crisis points to need for more infrastructure spending]

Clinton, who has enjoyed strong support among African American voters in the South, is expected to do well among black voters in Michigan, too. In 2008, 23 percent of voters who participated in Michigan’s Democratic primary were African American, according to exit poll data published by CNN.

The senator has increasingly hammered his opponent on trade, jobs and ties to Wall Street. On Friday, Sanders criticized Clinton’s support of trade agreements dating to the North American Free Trade Agreement, passed under her husband.

“If the people of Michigan want to make a decision about which candidate stood with workers against corporate America and against these disastrous trade agreements, that candidate is Bernie Sanders,” he said Friday.

“With another double-digit victory, we have now won by wide margins in states from New England to the Rocky Mountains and from the Midwest to the Great Plains,” the Sanders campaign said in a statement after the Maine win was announced. “This weekend alone we won in Maine, Kansas and Nebraska. The pundits might not like it, but the people are making history. We now have the momentum to go all the way to the Democratic National Convention in Philadelphia.”

And the Sanders campaign maintains that Michigan is ripe territory for the senator. Michigan has large numbers of working-class and struggling middle-class white voters and union members, a constituency that has gravitated toward Sanders elsewhere.Clinton delivered a speech on jobs and trade on Friday, telling workers at a woman-owned Detroit auto parts manufacturer that she opposes President Obama’s Trans-Pacific Partnership trade deal with Asian nations because it does not offer enough protection for American workers.

But she warned that protectionism is not the answer, either.

“There are people in both parties who think we can just shut ourselves away,” Clinton said. “But even if the United States never signs another trade deal, globalization isn’t going away.”

Michigan Democratic Party Chairman Brandon Dillon said the state’s Democrats are pleasantly surprised to be playing a significant role in the nominating contest this year. Although Michigan offers 147 delegates, one of the biggest delegate prizes during the first two months of voting, Dillon said Democrats here had assumed that the race would effectively be over by now. When the primary calendar was set last year, Clinton held a double-digit lead over all potential challengers.

“There’s a lot of excitement, especially around the debate and because when this started, people didn’t think much attention was going to be paid to Michigan,” Dillon said.

Izadi reported from Washington. Steve Friess in Flint contributed to this report.