(CNN) Bernie Sanders apologized for his aides' breach of Hillary Clinton's proprietary voter data in the opening moments of Saturday's Democratic debate -- and Clinton dropped the issue.

The two Democratic presidential hopefuls opted not to air out what has become a messy fight between their campaigns in front of the cameras as they met along with Martin O'Malley in Manchester, New Hampshire, for their third debate of the 2016 race.

Instead, Sanders opened the two-and-a-half hour debate by looking at Clinton and saying: "Yes. I'm sorry."

His comment provided a memorable start to a debate that also saw Sanders, Clinton and O'Malley trade blows on taxes, health care and guns -- while agreeing on their distaste for Donald Trump, the GOP front-runner. It seemed unlikely to alter the contour of the Democratic race six weeks before voting begins, while Clinton gave signs that she is already focused on the general election despite trailing Sanders in the state where the debate was held.

Sanders was apologizing after at least one campaign aide seized on a glitch in the Democratic National Committee-housed master voter list revealing Clinton campaign data usually protected by a firewall from opponents' eyes.

"This is not the type of campaign that we run, and if I find anybody else involved in this, they will also be fired," the Vermont senator said in response to Saturday evening's first question from ABC.

Clinton thanked Sanders for the apology.

"Now that, I think, you know, we've resolved your data, we've agreed on an independent inquiry, we should move on, because I don't think the American people are all that interested in this," the former secretary of state said.

Despite the public Kumbaya, there have been clear signs that the Sanders campaign sees the fight with the DNC -- which it's treating as a proxy for the broader Democratic establishment -- as advantageous.

His campaign has highlighted the DNC's move in fundraising notes to supporters, with strategist Tad Devine tweeted a comparison of the data-breach "mistake" to Clinton saying years ago that her vote to go to war in Iraq in 2003 was a mistake.

In person, Sanders couldn't resist letting a little resentment show, complaining that there had been "many press releases from the Clinton campaign of late" focused on the issue.

And Clinton, in what could have been a veiled message to early state Democratic activists, focused her closing statement on her ties to the party, playing the role of uniter against the GOP field while also providing a subtle reminder that Sanders has identified as an independent in Vermont.

She also played up the contrast with Republicans as she argued that the GOP would roll back hard-won gains on voting rights and gay rights and would defund Planned Parenthood.

"This is a watershed election. I know how important it is that we have a Democrat succeed President Obama in the White House," Clinton said.

Clinton felt good enough about her debate performance to end the night with a mic-drop moment -- winking at the new "Star Wars" movie.

"Thank you, good night, and may the force be with you," she said.

Still, at least two Clinton comments -- her dismissal of rising health care premium costs under the Affordable Care Act as "glitches" and her claim that "finally we are where we need to be" in the fight against ISIS -- will be clipped and saved by Republicans for a general election.

And she took some positions that could make progressives uneasy -- the former secretary of state broke new ground by pledging not to support any tax hikes on the middle class as she assailed Sanders' proposal to foot the bill for a paid family leave program that both candidates support.

Clinton criticized Sanders for backing a proposal to impose a 0.2% payroll tax -- deducted from checks much like Social Security and Medicare -- to cover his plan and said she'd never support higher taxes on all wage-earners to fund such a program.

"That is off the table as far as I am concerned," Clinton said, promising not to raise taxes on the middle class. "That is a pledge that I am making."

Instead, she said that she'd cover the cost of paid family leave with higher taxes on the wealthy.

Photos: Democratic debate in New Hampshire Photos: Democratic debate in New Hampshire Democratic presidential candidates Bernie Sanders, Hillary Clinton and Martin O'Malley debate at Saint Anselm College in Manchester, New Hampshire, on Saturday, December 19. The candidates met for their third debate. Hide Caption 1 of 8 Photos: Democratic debate in New Hampshire Sanders speaks as Clinton looks on during the debate. Sanders, at the start of the debate, apologized to Clinton for his staff's exploitation of a Democratic National Committee computer vendor's glitch to access her campaign's proprietary voter files. Hide Caption 2 of 8 Photos: Democratic debate in New Hampshire O'Malley speaks during the debate as Clinton looks on. Hide Caption 3 of 8 Photos: Democratic debate in New Hampshire Clinton speaks during the debate. Hide Caption 4 of 8 Photos: Democratic debate in New Hampshire Sanders speaks during the debate. Hide Caption 5 of 8 Photos: Democratic debate in New Hampshire O'Malley speaks during the debate. Hide Caption 6 of 8 Photos: Democratic debate in New Hampshire Sanders takes the stage. Hide Caption 7 of 8 Photos: Democratic debate in New Hampshire Clinton waves to a member of the crowd as she arrives on stage. Hide Caption 8 of 8

Sanders, though, responded that his plan is backed broadly by Senate Democrats. And he said Clinton's criticism of payroll taxes is out of step with Democratic giants such as Presidents Franklin D. Roosevelt, who oversaw the creation of Social Security, and Lyndon B. Johnson, who shepherded Medicare into law.

"What the legislation is is $1.61 a week. Now you can say that's a tax on the middle class. It will provide three months of paid family and medical leave," Sanders said, arguing it was well worth it.

The two also disagreed over health care, with Sanders arguing that his Medicare-for-all vision of ending private insurance would save Americans money, while Clinton warned that it would leave more power in the hands of Republican governors.

Sanders landed his biggest blow against Clinton when he assailed her support for ousting Libyan strongman Moammar Gadhafi and her push for a political end to Syrian President Bashar al-Assad's tenure.

"I worry too much that Secretary Clinton is too much into regime change and a little bit too aggressive without knowing what the unintended consequences might be," Sanders said.

Clinton shot back that Sanders had supported a congressional resolution calling for Gadhafi's removal in Libya.

She also warned against any policy that would allow Iran to increase its role in Syria, equating such a move to "asking the arsonist to come and pour more gas on the fire."

But Sanders stated, "We have got to get our foreign policy and our priorities right. It is not Assad who is attacking the United States -- it is ISIS."

The candidates once again struck different tones on gun rights -- with Clinton saying more citizens purchasing firearms wouldn't help matters and Sanders focusing on a search for "consensus" on gun regulations.

"Guns in and of themselves, in my opinion, will not make Americans safer. We lose 33,000 a year already to gun violence. Arming more people -- to do what? -- is not the appropriate response to terrorism," Clinton said.

Sanders, though, pointed to his state -- Vermont -- and said more than half of its residents own guns.

"I'm not going to say that everybody's in agreement -- it's a divided country on guns. But there is a broad consensus on gun safety regulation," Sanders said, calling for background checks for potential gun owners and the closure of loopholes that allow easier purchases at gun shows.

O'Malley, for his part, took a big swing at both candidates and charged that "Secretary Clinton changes her position on this every election year, it seems."

He continued, "What we need on this issue is not more polls. We need more principle."

The other candidates hit back -- with Sanders interjecting, "Whoa, whoa, whoa."

"We can do all the great speeches we want, but you ain't gonna succeed" without broad-based support, Sanders said.

But one topic brought all three candidates together: They really don't like Donald Trump.

"He is becoming ISIS' best recruiter," Clinton said, pointing to the billionaire businessman's proposal to ban Muslims from entering the United States.

"They are going to people showing videos of Donald Trump insulting Islam and Muslims in order to recruit more radical jihadists," she continued, though her contention hasn't been backed up.

O'Malley hit Trump on the same topic, saying that the United States "must never surrender our American values to racists, must never surrender them to the fascist pleas of billionaires with big mouths."

And Sanders, sticking to his income-inequality message, said to attendees of Trump rallies: "He thinks low wages are a good idea."

The debate also had its lighter moments, like when ABC moderator David Muir asked: "Should corporate America love Hillary Clinton?"

"Everybody should," Clinton responded.

Sanders took a different tone when asked the same question.

"No, I think they won't," he said, adding that "Wall Street will like me even less."

And at one point, Clinton was moments late in returning to the stage after a commercial break, leading the crowd to interrupt a question Muir had started to ask Sanders by cheering her tardy arrival.

"Sorry," Clinton said.