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 clashed fiercely Sunday over jobs, trade and Wall Street while agreeing that much more must be done to address a two-year-old water-contamination crisis that has paralyzed this majority-black city.

The session included the sharpest exchange yet between the Democratic presidential candidates over their economic plans and records. It included a heated argument over the auto industry bailout, which is of keen interest in Michigan, where both Democrats and Republicans will hold presidential primaries Tuesday.

Clinton emphasized the “hard choices” that lawmakers and President Obama made in 2009, facing the prospect of a collapse in the auto industry, and she noted that Sanders, a senator from Vermont, voted against a bailout measure.

Sanders said he voted against forcing “hard-working” Americans to bail out “the crooks of Wall Street.”

“If everybody had voted the way he did, I believe the auto industry would have collapsed,” Clinton said.

Sanders angrily hushed Clinton as she sought to interject. “Excuse me, I’m talking,” he said, drawing gasps from the audience.

“If you’re going to talk, tell the whole story,” Clinton replied.

“You’ll get your turn,” he snapped.

The debate, which aired on CNN, was added to the Democrats’ schedule after Sanders emerged as a stronger-than-expected challenger. Flint was chosen as the site to highlight the water crisis, which has become a focus of liberal anger.

The episode began two years ago, when state overseers who had taken over the city switched its water supply to the Flint River without treating the water to avoid corrosion of lead pipes. Lead leached into the water supply, and although residents began complaining immediately, the problems did not fully come to light until January, amid revelations that state officials had spent much of 2014 and 2015 dismissing those complaints.

Both Clinton and Sanders have said that the crisis would never have happened in a richer, whiter city. The debate featured heartbreaking and harrowing stories about children who stopped growing, lost their hair or were intellectually stunted by poisoned water.

Sanders used his opening statement to repeat his call for the state’s Republican governor to resign over what he called a “dereliction of duty,” before shifting to his core message about economic inequality.

For the first time, Clinton agreed that Gov. Rick Snyder should “resign or be recalled.” Previously, she had said that her approach was to try to solve the problem and that assigning blame could wait.

“The state should also be sending money immediately to help this city. I know the state of Michigan has a rainy-day fund for emergencies,” Clinton said. “It’s raining lead in Flint.”

Sunday’s debate opened with a moment of silence in honor of former first lady Nancy Reagan, who died Sunday at 94. The session was the first Democratic debate 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 win in Louisiana on Saturday, while Sanders claimed victories in Nebraska and Kansas. The debate had been underway for only a few minutes Sunday when Sanders’s victory in the Maine caucuses was announced.

Sanders’s successes and his vow to remain in the race through the Democratic convention lent a new tension to the debate. Gone were the magnanimous and polite gestures each had offered the other in previous debates.

“Let’s have some facts instead of some rhetoric for a change,” Clinton said testily.

“Let me tell my story, you tell yours,” Sanders said at another point. “Your story is voting for every disastrous trade amendment and voting for corporate America.”

Sanders mocked Clinton’s defense of the Export-Import Bank as helpful to small businesses. He would shutter the institution he called the “Bank of Boeing” for its efforts on behalf of the aircraft maker as it competes with rival Airbus.

Sanders’s opposition to the Ex-Im Bank put him at odds with the Democratic caucus in Congress — a fact that he embraced.

“I don’t want to break the bad news,” Sanders said sarcastically. “Democrats are not always right. Democrats have often supported corporate welfare. Democrats have supported disastrous trade agreements.”

Both candidates have campaigned hard in Michigan. Tuesday’s vote here will serve as a test of Clinton’s institutional support from unions and of Sanders’s appeal with the working class.

It could also set the stage for a contentious fall election. Clinton has already begun shifting her focus on the campaign trail to a potential general-election matchup against the Republican front-runner, Donald Trump, although neither he nor the rest of the Republican field got much mention Sunday.

“Donald Trump’s bigotry, his bullying, his bluster are not going to wear well with the American people,” Clinton said.

Labeling Sanders a communist “was one of the nice things he said about me,” Sanders joked.

Michigan is a swing state that both Republicans and Democrats see as a potential victory in November. Trump is favored to win here Tuesday, and his tough-guy message on international trade has found an audience here.

Over several days of campaigning here, Sanders has focused squarely on jobs and trade, accusing Clinton of backing international trade deals that stripped Michigan of good-paying jobs.

He also stressed his long opposition to trade pacts such as the pending Trans-Pacific Partnership with Pacific Rim nations. Clinton had backed the TPP deal, a signature initiative of President Obama, when she was secretary of state. She announced last year that she opposes it, which Sanders allies call an election-season conversion that she could reverse if elected.

“I am very glad, Anderson, that Secretary Clinton has discovered religion on this issue,” Sanders said to moderator Anderson Cooper. “But it’s a little bit too late.”

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

But with momentum from other primaries that featured large numbers of African American voters, Clinton holds a comfortable lead in Michigan. She has focused her campaign here on black voters, who were about a quarter of the primary electorate in 2008, and on the Flint crisis.

A Detroit Free Press-WXYZ poll released late Saturday shows her leading Sanders by 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 poll had her in a statistical tie with Sanders on the question of trustworthiness and up three points on the question of who would be the “more progressive president.” Only 17 percent of those polled felt Sanders had the best chance of winning in November.

At a news conference before the debate, Sanders acknowledged that he trails Clinton in Michigan, in part because he has continued to struggle to reach African American voters, who represented about 23 percent of the Democratic primary electorate in 2008.

During the debate, he fumbled a question about what “racial blind spots” he has by suggesting that only black people live in ghettos.

“When you’re white, you don’t know what it’s like to be living in a ghetto, you don’t know what it’s like to be poor, you don’t know what it’s like to be hassled when you walk down the street or when you get dragged out of a car,” he said.

For her part, Clinton misstated her own position on gun control, a central issue in her campaign.

“I think we have to try everything that works to try to limit the number of people and the kinds of people who are given access to firearms,” she said.

That goes further than her official position that loopholes in existing gun-control laws should be narrowed and that people on the federal terrorist no-fly list should be prevented from buying guns.

Despite predicting a continued strong challenge from Sanders, Clinton’s advisers hope that by April, her delegate advantage will make it virtually impossible for Sanders to claim the nomination.

The catastrophic failure represented by the Flint water crisis set the tone for the feisty debate, with both candidates expressing outrage and promising action.

“President Sanders would fire anybody who knew about what was happening and did not act appropriately,” Sanders said.

Sanders also demanded a rebate for Flint residents who paid their water bills throughout the crisis, something that has already been done. Snyder has obtained a $30 million appropriation to pay Flint water bills and give residents money back.

“You are paying three times more than poisoned water than I pay in Burlington, Vermont, for clean water,” Sanders said.

Clinton pledged to “get rid of lead everywhere” within five years if she is elected.

Elahe Izadi in Washington and Steve Friess in Flint contributed to this report.