Fresh off a series of weekend victories in state caucuses, Bernie Sanders turned up the heat on Hillary Clinton at Sunday’s debate in Flint, Mich., sharply challenging her economic credentials and suggesting her gun control stand would ban guns in America. But the Democratic front-runner fought back, blasting him for voting against the auto bailout, dismissing him as a “one-issue candidate” and hitting him once again for his stance on guns.

The Vermont senator reached back to the 1990s as he went after Clinton’s support for “disastrous trade agreements” like NAFTA. His rhetoric was notably more pointed and, reflecting the tension in the race, Sanders even cut her off at times as she tried to speak over him.

“Excuse me, I’m talking,” Sanders snapped, during one feisty exchange on the economy.

But Clinton pushed back, and defended the country’s economic progress during her husband’s administration.

“If we’re going to argue about the ‘90s, let’s try to get the facts straight,” she said, touting the jobs and income growth that came with the era.

Sanders also tried to cast Clinton as soft on climate change, while declaring he unequivocally does not support fracking. Clinton maintained she has the “most comprehensive plan to combat climate change.”

The clashes came after Sanders won the Maine Democratic caucuses, adding to wins the night before in Nebraska and Kansas — by far the most successful two days of his campaign.

But Sanders remains significantly behind in the race for delegates, with Clinton having won more – and more valuable – state contests, as well as enjoying the overwhelming support of so-called “superdelegates.” Sanders is looking for a game-changer as the race heads next to states like Michigan this coming Tuesday, and Ohio and Florida the week after that.

Sanders cited his most recent wins at the end of Sunday’s debate, in arguing he would be the better candidate to go up against Republican front-runner Donald Trump.

He began to joke he’d give his “right arm” to run against the billionaire businessman and then cited polls saying, “Sanders versus Trump does a lot better than Clinton versus Trump.”

But while Sanders said he’s “exciting” working-class and young voters, Clinton pointed to the raw numbers.

“There’s only one candidate [in either primary campaign] who has more votes than [Trump], and that’s me,” Clinton said. “I will look forward to engaging him.”

With the CNN-hosted debate held in Michigan, the state’s economic and crime problems were front and center.

On gun control, the two candidates sparred sharply, with Clinton using the Sandy Hook massacre to make a point about holding gun makers responsible for crimes – and Sanders arguing that position would effectively mean an America without guns.

The dispute started when Sanders defended his past support for a bill to help protect gun manufacturers and sellers from lawsuits. He said if gun sellers and makers are held liable in many of these cases, “What you’re really talking about is ending gun manufacturing in America.”

Clinton countered that no other industry in America has “absolute immunity,” and invoked the Sandy Hook mass shooting.

The Democratic rivals were most heated when talking about their respective records on the economy. Sanders went after Clinton over what he called “disastrous trade agreements” like NAFTA.

She countered by pointing out he opposed the auto industry bailout. He tried to describe it as the Wall Street bailout, and got a little feisty when she started to speak over him.

“Excuse me, I’m talking,” he said. “Your story is for voting for every disastrous trade agreement.”

Clinton then called him a “one-issue candidate.” And on the auto bailout, she said, “If everybody had voted the way he did, I believe the auto industry would have collapsed, taking 4 million jobs with it.”

“My one issue is trying to rebuild a disappearing middle class. That’s my one issue,” Sanders said.

Meanwhile, at the top of the debate, Clinton and Sanders momentarily set aside their differences, to lament the plight of the people in the host city of Flint, and call for the governor’s resignation over the toxic water crisis.

Sanders said there’s “blame to go around” but Republican Gov. Rick Snyder should resign.

Clinton echoed the remarks, saying, “Amen to that.”

“The governor should resign or be recalled,” she said, while also calling on the federal and state governments to send more money to the city.

The city’s water crisis started when the city switched to the Flint River in 2014 while under a state-appointed emergency manager. While the state has taken much of the blame, officials with the city and federal government – as well as the state – have also resigned.

Clinton faced Sanders on the debate stage as she fights to shake her lone primary rival, who keeps notching just enough primary and caucus wins to keep his campaign alive, and a threat to her bid.

Sanders rode to victory in Maine in part on a huge turnout — Sanders beat Clinton by a ratio of nearly 2-to-1. The turnout was so big Sunday that some voters had to wait in line for more than four hours in Portland.

The victory gives Sanders a total of three victories over the weekend to Clinton’s one, in the Louisiana primary.

The results from Maine Sunday aren't binding, but will be used to select a slate of delegates to the state convention, where national delegates will be elected. Maine will send 25 delegates and 30 superdelegates.

On Super Tuesday last week, Clinton won seven states to Sanders’ four. She maintains a sizeable delegate lead – which before the Maine contest stood at 1,121 to 481. It takes 2,383 delegates to win the nomination.

But Sanders, even by winning lower-profile contests, has managed to at least demonstrate lingering weaknesses in the front-runner’s campaign as he draws an enthusiastic response in the grassroots-driven caucus states. Sanders sees upcoming Midwestern primaries as a crucial opportunity to slow her momentum by highlighting his trade policies – though Clinton has led in the polls in Michigan.

“Geographically, we’re looking good,” Sanders said Sunday on ABC’s “This Week.” “We have a path.”

Sanders acknowledged his campaign has yet to connect with African-American voters, which hurt him badly in his South Carolina loss last month to Clinton.

However, he told ABC, “I think you’re going to see those numbers change.”

The Associated Press contributed to this report.