Third Democratic Presidential Debate: 9 Moments That Mattered

MANCHESTER, New Hampshire -- At the final Democratic presidential primary debate of the year, tensions boiled over gun control, how to combat terrorism and the controversy that dominated the past 48 hours: A breach of the national party’s voter database.

The debate, hosted by ABC News and moderated by “World News Tonight” anchor David Muir and Chief Global Affairs Correspondent Martha Raddatz, featured some of the most intense sparring yet, between former Secretary of State Hillary Clinton, Vermont Sen. Bernie Sanders and former Maryland Gov. Martin O’Malley.

It began with an apology from Sanders to Clinton for a now-fired campaign employee who accessed some of her proprietary campaign data after a glitch from a Democratic National Committee’s computer vendor exposed it.

But that’s where the contrition ended.

The attacks flew between the three candidates at the debate at St. Anselm College in New Hampshire, where despite Clinton’s sweeping national lead, Sanders remains competitive. The most recent Boston Herald poll found a tight race in the Granite State: Sanders at 48 percent and Clinton at 46 percent.

With just 43 days until the Iowa caucuses and 51 days until the New Hampshire primary, here are 9 moments that mattered at Saturday night’s debate:

1. Sanders Says He’s Sorry

Vermont Sen. Bernie Sanders kicked off the debate by apologizing to Hillary Clinton for a campaign aide who accessed her campaign’s private data. That aide has since been fired.

"Yes, I apologize," he said when asked by Muir whether Clinton was owed an apology. "Not only do I apologize, I want to apologize to my supporters. This is not the kind of campaign that we run.”

Clinton responded: “I very much appreciate that comment, Bernie. We should move on because I don't think the American people are all that interested in this.”

But former Maryland Gov. Martin O’Malley was having none of it. “For crying out loud, our country has been attacked,” he said, pointing to issues that he said were more important. “Instead, we're listening to the bickering back and forth.”

Sanders’ remarks came after a bug in the firewall of the Democratic Party’s voter data software allowed four Sanders staffers to access files belonging to the Clinton campaign.

2. Clinton Calls Trump ‘ISIS’ Best Recruiter’

Clinton took several opportunities to take direct aim at Republican front-runner Donald Trump, at one point citing his rhetoric as a powerful and potent tool for the Islamic State.

“He is becoming ISIS's best recruiter,” Clinton said. “They are going to people showing videos of Donald Trump insulting Islam and Muslims in order to recruit more radical jihadists.”

Clinton provided no further evidence to back up her claim, and ABC News reached out to the Clinton campaign for comment.

In the wake of the ISIS-inspired mass killing in San Bernardino, Calif. earlier this month, Clinton also said she does not believe calls to arm more Americans -- an idea that Trump has pushed -- will make Americans safer.

“Guns, in and of themselves, in my opinion will not make Americans safer,” she said. “We lose 33,000 people a year already to gun violence. Arming more people to do what I think is not the appropriate response to terrorism.”

3. Sanders’ Moment Of Zen

Sanders -- usually one of most animated orators in the 2016 field -- ended up being the one to tell one of his own rivals to “calm down.”