DES MOINES, Iowa — As tensions flare and polls tighten in the final weeks before Iowa’s critical caucus, the leading candidates for the Democratic presidential nomination faced off back-to-back in a forum focused on minority issues Monday night.

At the Iowa Black and Brown Forum, broadcast on the Fusion network, Democratic front-runner Hillary Clinton broke with President Obama to call for a stop to Department of Homeland Security deportation raids targeting undocumented Central American migrants.

They “have sown fear and division in immigrant communities across the country” in recent weeks, she said. Last month, Clinton said she had “real concerns” about the raids but did not go as far as she did Monday night.

“Our immigration enforcement efforts should be humane and conducted in accordance with due process, and that is why I believe we must stop the raids happening in immigrant communities,” Clinton said in a statement released during the forum. “We have laws and we must be guided by those laws, but we shouldn’t have armed federal officers showing up at peoples’ homes, taking women and children out of their beds in the middle of the night."

Related: Hillary Clinton Calls for End to Immigration Raids

Clinton could not answer whether she’d deport children as president, saying it was more complicated than a yes or no answer. When pressed, Clinton simply said children would receive “due process.”

And in a comment that the Sanders campaign is already looking to exploit, Clinton acknowledged that she voted for border security, but said it included funding for a fence not a wall.

With just 20 days until the Iowa Caucuses, a new NBC News/Wall Street Journal/Marist poll shows an essentially tied race. Clinton’s lead over Sanders has slimmed to a mere three percentage points in Iowa, while Sanders’s lead in New Hampshire has tightened to four points.

The Morning Rundown Get a head start on the morning's top stories. This site is protected by recaptcha

Clinton, who rarely utters her chief rival’s name, stepped up her attacks on Sanders this week, methodically picking fights him on Wall Street, guns,electabilityand health care. Sanders and his campaign see this as a sign of strength.

Asked if Clinton is getting more aggressive, Sanders responded with a long, drawn out, “Yes.” Why? "It could be that the inevitable candidate for the Democratic nomination may not be so inevitable today,” he said. Earlier in the day, he said the attacks were a sign that Clinton’s campaign is in “serious trouble.”

Clinton denied that her attacks are a response to the polls in an interview with MSNBC’s Chris Hayes Monday night before the forum. “No, it's really not,” she said. “I always thought this would be a close race, I've been around the track a few times, as you know, and it always closes. Iowa's famously unpredictable.”

Meanwhile, at the forum, Sanders defended a controversial 2005 vote for a law that gave gun manufacturers and sellers immunity from lawsuits. “It’s not a mistake, like many issues of legislation it’s complicated,” Sanders said. “You are a small gun shop owner in the state of Vermont, you sell her a gun legally, she goes through the instant background check. Then she goes out later and shoots somebody. Should she be sued? No, I don’t think so.”

Clinton has repeatedly attacked her challenger for the vote, saying he sided with the National Rifle Association. And President Obama suggested in a recent op-ed that he might not campaign for Democratic candidates who don’t oppose the law.

Asked about sexual harassment on college campuses, Sanders said that in addition to cracking down on abuse, “We really do need a serious national discussion about sexuality." He also said be believed more progress had been made on sexism than racism, pointing to police killings of black people.

In a lightning round of lighter questions, Sanders said he was not familiar with musician David Bowie, who died this week. Asked if a Democratic socialist can live in a mansion like the White House, he joked, "I would consider it more like public housing." And he said his favorite fictional president is Michael Douglas’ character Andrew Shepherd in “The American President,” whom he deemed “cool.”

In her exchange with the Fusion moderators, Clinton mostly steered clear of Sanders. Asked how’s she benefited from white privilege, Clinton replied, “Where do I start?”

She also called for a repeal of the Hyde Amendment, which prohibits the use of federal funds for abortion. "Yes, I think we should do everything we can to repeal the Hyde Amendment,” she said.

When asked if she could say definitively that Sanders would not win the presidency, Clinton laughed and said, “Anybody can win. Who would have thought Donald Trump would be leading in national polls?"

Former Maryland Gov. Martin O’Malley, who is stuck in the low single digits in polls with just days to go, poked fun at his limited support. "My wife asked me what I wanted for Christmas and I said two more points in an Iowa poll, please,” he said.

He also joked that he was only one who "can still upset the apple cart." But he blamed the Democratic National Committee for his struggle, saying they’ve prohibited the candidates from having more debates and tipped the nominating process in favor of Clinton.

Clinton did her best to avoid saying Donald Trump’s name, but that didn’t prevent her from giving a gift to all of his Republican opponents.

Asked about attending Trump’s wedding, she noted, "He was basically a Democrat before he was a Republican."