Last Updated Jan 18, 2016 1:10 AM EST
10:50 p.m. The audience erupts into laughter as the candidates are offered the chance to say something they really want to say, and O'Malley -- who frequently interjects to try to get more speaking time in debates -- breaks into a smile.
"There are so many issues we haven't been able to discuss here," he said, including immigration reform, the Puerto Rican debt crisis, and possible nation state failures in the Western hemisphere due to drug traffickers.
"We are a great people when we act at home and abroad based on the beliefs that unite us. He called for "new leadership that can heal our divides here at home and bring our principles into alignment abroad."
Clinton said she has spent the last week being "outraged" by the crisis over lead-tainted drinking water in Flint, Michigan, a subject she also discussed on CBS' "Face the Nation" Sunday morning.
"Let me tell you what if the kids in a rich suburb of Detroit had been drinking contaminated water and being bathed in it there would have been action," she said, suggesting that Flint was ignored because its residents are mostly African American and poor.
Sanders echoed her anger and said he had demanded the resignation of Gov. Rick Snyder for his slow response to the crisis.
"A man who acts that irresponsibly should not stay in power," he said.
Then he launched into some typical campaign talking points.
"We've heard a lot of great ideas here tonight but let's be honest and let's be truthful. Very little is going to be done to transform our economy and to create the kind of middle class we need unless we end a corrupt campaign finance system that is undermining American democracy. We have got to get rid of super PACs, we have got to get rid of Citizens United and what we have got to do is create a political revolution which revitalizes American democracy," he said.
10:46 p.m.Mitchell asks Sanders whether he regrets calling former President Bill Clinton's transgressions disgraceful.
"That question annoys me," he said. "I cannot walk down the street...without being told how much I have to attack Secretary Clinton."
Pressed on the issue, he said he is trying to run an issues-oriented campaign, "His behavior was deplorable. Have I ever once said a word about that issue? No I have not."
10:42 p.m. Holt wants to know whether Bill Clinton will have a "kitchen table" advisory role or a "real policy role" if she is elected president.
"It will start at the kitchen table and we'll see where it goes from there," Clinton said, to laughter. "I'm going to have the very best advisers I can possibly have."
"You bet I'm going to ask for his ideas, I'm going to ask for his advice, and I'm going to use him as a goodwill emissary to go around the country and find the best ideas we've got," she added.
In his response, Sanders said that Clinton and O'Malley would have Wall Street advisers in his cabinet.
"Goldman Sachs is not going to have...a secretary of treasury for a Sanders administration," he said.
10:30 p.m. Another foreign policy question is directed at Clinton as she is asked if she would hand Russian President Vladimir Putin a "reset button" to restart relations like the two nations tried in 2009.
"It would depend upon what I got for it," Clinton said. She argued in 2009 the U.S. got a new START treaty, permission to resupply troops in Afghanistan across Russia, and got Russia to sign onto sanctions against Iran.
Then she was asked what her relationship is like with Putin.
"It's interesting" Clinton said, proceeding slowly. "It's one I think of respect, we've had some very tough dealings with one another and I know that he's someone that you have to continually stand up to because like many bullies he is someone who will take as much as he can unless you do."
10:27 p.m. One area of "honest disagreement" with Clinton, Sanders says, is on U.S. priorities in the region. Sanders said the first priority must be the destruction of ISIS, the second priority should be getting rid of Assad -- working with both Iran and Russia.
10:24 p.m. Mitchell asks Clinton whether the president should have stuck to his "red line" and struck Syria after President Bashar Assad used chemical weapons on his own people. Did the U.S. hurt its own credibility?
"The president's decision to go after the chemical weapons once there was a potential opportunity to build on...resulted in a very positive outcome. We were able to get the chemical weapons out," Clinton said.
10:22 p.m. Sanders is asked whether Obama's decision to pull all troops out of Iraq in 2011 led to a vacuum that allowed the Islamic State of Iraq and Syria (ISIS) to amass so much power.
"No, I think the vacuum was created by the disastrous war in Iraq which I vigorously opposed," he said. "It's easy to get rid of a two-bit dictator like Saddam Hussein but there wasn't enough thought given to what happens the day after you get rid of him."
10:20 p.m. Though they have many disagreements on foreign policy, Clinton and Sanders do agree that there should not be U.S. ground troops fighting in Syria.
10:17 p.m. Is it time to restore diplomatic relations with Iran?
"I think what we have got to do is move as aggressively as we can to normalize relations with Iran, understanding that Iran's behavior in so many ways is something that we disagree with," Sanders said.
"Can I tell you that we should open an embassy in Tehran tomorrow? No, I don't think we should," he added, but said the U.S. should work to "warm"relations with Iran as it did with Cuba.
Clinton said the U.S. must still watch Iran closely.
"We need more good days before we move more rapidly toward any kind of normalization," she said.
10:08 p.m. The candidates are asked how to convince Americans that climate change is so urgent they must act.
"Younger generation understands it instinctively. I was home in Burlington, Vermont on Christmas Eve, the temperature was 65 degrees. People understand what's going on," he said.
For a moment, he turns the attention back onto the Republicans and criticizes them for casting doubt on climate change. He gets a laugh from the audience when he says Republican candidate Donald Trump ""believes that climate change is a hoax invented by the Chinese."
O'Malley calls on his fellow candidates to join him in pushing for a 100 percent clean electric energy grid by 2050.
10:04 p.m. Sanders is asked whether he is going back on a pledge to only raise taxes to pay for childcare since his healthcare plan released Sunday would raise taxes for health care as well.;
"If I save you $10,000 in private health insurance and you pay a little bit more in taxes in total, there are huge savings in what your family is spending," he said.
10:01 p.m. Mitchell asks Sanders about how he will pay for his plans including debt-free college and raising the minimum wage. Just hours before the debate, he said he would pay for his health care plan with higher payroll taxes, a health care premium and a top marginal tax rate of more than 50 percent. He says other initiatives will be paid for with a tax on Wall Street speculation.
Clinton says she's the only candidate who has said she will not raise taxes on the middle class. "I'm going to do everything I can to make sure the wealthy pay for debt-free tuition, for childcare, for paid family leave," she said.
10:00 p.m. As the argument over the economy continues, Clinton goes on the attack against Sanders, saying he voted in favor of deregulation in 2000.
9:56 p.m. Clinton tries another line of defense.
"The hedge fund billionaires who are running ads against me right now...funded by money from the financial services sector sure think I'm the one they don't want to be up against."
O'Malley said he is the person who will put cops back on the Wall Street "beat" and says he has a lot of daylight with Clinton.
"You did not go as far on reigning in Wall Street as I would," he said. "The people of America deserve to have a president who is on their side."
9:53 p.m. Sanders offers some tough criticism of Clinton when asked about how they differ on dealing with banks.
"I don't get personal speaking fees from Goldman Sachs," Sanders said.
Clinton responded with a big embrace of President Obama.
"Sen. Sanders called him weak, disappointing, he even in 2011 sought someone to run in a primary against President Obama. Now I personally believe that President Obama's work to push through the Dodd-Frank bill and then to sign it was one of the most important regulatory schemes we've had since the 1930s. So I'm going to defend Dodd-Frank, and I'm going to defend President Obama," she said, to loud applause.
Sanders came back his original argument, saying that people "have doubts" about the ability of someone who receives donations from Wall Street to regulate the banks.
9:47 p.m. Clinton largely dodges a question about why Sanders is polling so much better among young voters than she is.
"I'm going to keep working as hard as I can to reach as many people of all ages about what I can do," she says.
9:42 p.m. Sanders is asked about his affiliation as a Democratic socialist. He said the Democratic Party needs "major reform."
"We need a 50-state strategy so that people in south Carolina and Mississippi can get the resources that they need. Instead of being dependant on super pacs what we need is to be dependant on small, individual campaign contributers. We need an agrenda that speaks to the needs of working families," he said.
O'Malley hits Clinton and Sanders for not coming to run for Vincent Shaheen, the Democrat who challenged South Carolina Gov. Nikki Haley in 2014.
9:38 p.m. Clinton reiterates again that the party should not start over on healthcare.
"This has been the fight of the Democratic Party for decades. We have the Affordable Care Act. Let's make it work," she said, noting that a public option -- which would have allowed people to essentially buy into Medicare -- could not pass even when Democrats controlled the White House and Congress.
9:36 p.m. Mitchell tries to ask Sanders about why a proposal similar to his was rejected in Vermont because it would have required a major tax increase. Sanders said it is a better question for the governor.
"When we are talking about healthcare, the details really matter and therefore we have been raising questions about the nine bills he introduced over 20 years, as to how they would work," Clinton said. "He didn't like that, his campaign didn't like it either and tonight he's come out with a new plan and again we need to get into the details."
"I don't want to see us start over again with a contentious debate," she added.
"Secretary Clinton didn't answer your question," Sanders said, before going on to defend his record pushing for universal healthcare throughout his career.
Citing advances like ensuring that people cannot be excluded for pre-existing conditions, Clinton reiterated that Democrats should not begin rewriting health care legislation.
"We are going to go forward," Sanders said, saying that Clinton has not addressed how people are underinsured despite having huge copays. He said he does not want to rip up Obamacare.
"I think instead of attacking one another on healthcare, I think we should be talking about what is working," O'Malley said, jumping in.
9:25 p.m. The candidates are fielding questions about how to deal with the rising epidemic of heroin addiction. Read more about the candidates' plans here.
Sanders said he agrees with much of what Clinton said -- police officers must be equipped with the drug to treat a heroin overdoes, addiction should be treated like a disease rather than a crime, and there should be more people diverted from the criminal justice system into drug courts, treatment and recovery.
But he also added that, "there is a responsibility on the part of the pharmaceutical companies and the drug companies who are producing all of these drugs and not looking at the consequence of it."
9:23 p.m. The discussion of racial issues continues with a question to Sanders from a YouTube user about how to ensure that investigations of police violence are fair. Sanders talks about a commitment to investigating public officials accused of wrongdoing and the need to take steps like demilitarizing police departments.
9:20 pm. Sanders is asked about the fact that the chair of the Congressional Black Caucus, Rep. G.K. Butterfield, D-North Carolina, endorsed Clinton and that she polls so much higher among minorities.
"When the African American community becomes familiar with my congressional record and with our agenda and with our views on the economy and criminal justice, just as the general population has become more supportive, so will the African American community, so will the Latino community," he said, pointing to the fact that he has risen up from just 3 percent in the polls to running close to even with Clinton in Iowa and New Hampshire.
9:18 p.m. Clinton is asked about the death of Walter Scott, the unarmed black man who was shot and killed while running from a traffic stop in South Carolina. Holt asked about a perception among black men that their lives are cheap.
"Sadly its reality, and it has been heartbreaking and incredibly outraging to see the constant stories of young men like Walter Scott like you said who have been killed by police officers. There needs to be a concerted effort to address the systemic racism in our criminal justice system," she said.
9:12 p.m. Right off the bat moderator Lester Holt presses Sanders over agreeing to revisit legislation protecting gun manufacturers and sellers from liability when guns are used in the commission of a crime. He reiterated that he supports ending immunity as long as there are some protections for small, "non-negligent," "mom and pop" gun shops.
In response, Clinton ticked off the reasons she believes Sanders does not have a record of supporting gun safety measures, including voting against the Brady Bill that mandated background checks.
"I am pleased to hear that Sen. Sanders has reversed his position on immunity and I look forward to him joining with members of Congress who have already introduced legislation." She said no other industry gets the "total pass" that gun manufacturers do.
O'Malley argues that both Clinton and Sanders have inconsistent records on gun issues and talked about Maryland passing comprehensive gun safety legislation that banned assault weapons and mandated background checks.
"We did not interrupt a single person's hunting season. I have never met a self-respecting deer hunter that needed an AR-15," he said.
9:10 p.m. The moderators ask the candidates to lay out their top three priorities for their first 100 days in the first question. Sanders says, "end the decline of the middle class...tell the wealthiest people in this country that yes they are going to start paying their fair share of taxes and that we are going to have a government that works for all of us." Both Clinton and O'Malley rattle off a long litany of priorities including introducing their various plans to create jobs, immigration reform and equal pay.
9:06 p.m. All three candidates mention Martin Luther King Jr. in their opening statements. The debate takes place the day before the holiday marking the leader's birthday.
8:45 p.m. The three remaining Democrats will soon take the stage for their fourth debate, and first of 2016. The most focus will be on former Secretary of State Hillary Clinton and Sen. Bernie Sanders, I-Vermont, who are in an increasingly tight race in both Iowa and New Hampshire.
Former Maryland Gov. Martin O'Malley is also on stage, although he hasn't yet cracked single digits.
The past several weeks have seen Clinton and Sanders spar over gun control and healthcare. Sanders has also sought to undercut Clinton's argument that she is the only one who could win in a general election. During the sixth Republican debate Thursday, Sanders tweeted a graphic showing he could beat Trump and all of the other top GOP candidates.
NBC Nightly News anchor Lester Holt is serving as the main moderator during the debate. NBC News' chief foreign affairs correspondent Andrea Mitchell will also ask questions and others will be submitted by YouTube users.