The beginning of the debate focused on health care, specifically Medicare for All, and it highlighted the tensions and differences between Democrats on this issue.

While Warren was telling the story of Ady Barkan, a man who has amyotrophic lateral sclerosis (ALS), moderator Jake Tapper interrupted her. There was light laughter in the audience, and Warren cut that short, saying, "This isn't funny."

"This is somebody who has health insurance and is dying," she said. "Every month he has about $9,000 in medical bills that his insurance company won’t cover."

Also during the health care conversation, Rep. Tim Ryan challenged Sanders on Medicare for All, saying perhaps Sanders didn't totally understand the data and specifics behind it.

"I do know that," Sanders replied. "I wrote the damn bill."

Asked about mass shootings, after three people — including two children — were killed and 12 were injured at the Gilroy Garlic Festival in California, Mayor Pete Buttigieg got personal about the way mass shootings have affected children's education.

"I was a junior when the Columbine shooting happened. I was part of the first generation that saw routine school shootings. We have now produced the second school shooting generation," he said. "We dare not allow there to be a third. Something is broken."

As a few candidates on stage were talking about the effect that special interest money in politics can have, particularly in the case of the National Rifle Association (NRA), author Marianne Williamson touted her non-political background.

"They've taken tens of thousands, in some cases hundreds of thousands, from these same corporate donors, to think that they now have the moral authority to say we're going to take them on, I don't think the Democratic Party should be surprised that so many Americans believe yada, yada, yada," she said. "It is time for us to start over with people who have not taken donations from any of these corporations and can say with real moral authority, that is over, we are going to establish public funding for federal campaigns."

In response to former Rep. John Delaney, who argued that "Democrats win when we run on real solutions, not impossible promises," Warren countered that that's not the way to look at it.

"I don’t understand why anybody goes to the trouble of running for president of the United States just to say all the things we can’t do and shouldn’t fight for," Warren said.

Delaney responded, "I'm as big of a dreamer and an entrepreneur as anyone, but I also believe we need to have solutions that are workable."

The conversation moved on to race in America — an important issue many people were wondering if the debate would touch on, considering that during the first night, the candidates were all white. Warren was asked how she would combat white supremacy.

She began: "We need to call out white supremacy for what it is: domestic terrorism. And it poses a threat to the United States of America.

"We live in a country where the president is advancing environmental racism, economic racism, criminal justice racism, health care racism," she added. "The way we do better is to fight back and show something better."

Former Rep. Beto O'Rourke gave an answer on supporting reparations, saying he would sign Sheila Jackson Lee's reparations bill into law. But Williamson, who has spoken strongly in favor of reparations before, responded in a way that garnered her massive applause.

"First of all, it's not $500 billion in financial assistance," she said. "It's $500 billion, $200 to $500 billion payment of a debt that is owed. That is what reparations is. We need some deep truth telling.

"We need to recognize that when it comes to the economic gap between blacks and whites in America, it does come from a great injustice that has never been dealt with."

She added: "If you think any of this wonkiness is going to deal with this the dark, psychic force of the collectivized hatred that this president is bringing up in this country, then I'm afraid the Democrats are going to see some very dark days."

Night 2

To kick off the second night, former Housing and Urban Development Secretary Julián Castro became the first candidate to mention Puerto Rico during the debates. Puerto Rico mobilized in protests over the past couple of weeks after the governor's group chat, which included homophobic, misogynistic, classist, and racist rants, was leaked to the public. The governor stepped down last week.

"We were reminded and inspired by our fellow Americans in Puerto Rico that public service isn't about any of us, it's about you and your family," he said.

There were two big moments of protests in the first hour of the second debate. The first came while Sen. Cory Booker was giving his opening statement. Chants of "fire Pantaleo" echoed through the debate hall, clearly meant for New York City Mayor Bill de Blasio. Daniel Pantaleo is a NYPD police officer who killed Eric Garner in 2014. The Justice Department declared two weeks ago that they would not bring federal charges against the officer.

The second moment of protests came while the candidates were discussing immigration. Protesters interrupted Biden with chants of "3 million deportations," calling out the Obama administration's problematic immigration policies.

Moderator Dana Bash started the debate by asking Harris: "This week you released a new health care plan which would preserve private insurance and take 10 years to phase in. Vice President Biden's campaign calls your plan, quote, 'a have-it-every-which-way approach' and says it's just part of a confusing pattern of equivocating about your health care stance. What do you say to that?"

Harris gave her answer, explaining there will be a public and private Medicare option for families. Biden had a chance to respond.

"The senator has had several plans so far," he said. "And any time someone tells you you're going to get something good in 10 years, you should wonder why it takes 10 years. If you noticed, there is no talk about the fact that the plan in 10 years will cost $3 trillion. You will lose your employer-based insurance. And in fact, you know, this is the single most important issue facing the public. And to be very blunt and to be very straightforward, you can't beat President Trump with double-talk on this plan."

Harris then replied, "Unfortunately, Vice President Biden, you're just simply inaccurate in what you're describing. The reality is that our plan will bring health care to all Americans under a Medicare for All system."

As the candidates all discussed their positions on immigration — keeping families together (Bennet), treating illegal border crossings as civil violations (Gillibrand), keeping a white nationalist out of the Oval Office (Inslee) — the spotlight eventually turned to Biden.

"The fact of the matter is if you cross the border illegally you should be able to be sent back; it's a crime," he said.

Castro responded, "Mr. Vice President, it looks like one of us has learned the lessons of the past and one hasn't."

Biden also mentioned that "anyone with a Ph.D. should be issued a green card," something Booker took issue with as reinforcing the idea of there being an ideal type of immigrant.

"That’s playing into what the Republicans want: to pit some immigrants against other immigrants," Booker said. "Some are from shithole countries. Some are from worthy countries."

And de Blasio also joined in, mentioning Obama's record on deportation.

"You were vice president of the United States," de Blasio said. "I didn't hear whether you tried to stop them or not using your power in the White House. Did you think it was a good idea or something that needed to be stopped?"

The conversation turned to criminal justice reform, and Biden was pressed on his crime bills that most say resulted in the mass incarceration of black people. The former VP tried to change the topic, pointing to how Booker handled the police department as mayor of Newark, New Jersey.

"We have a system right now that is broken, but if you want to compare records, and I am shocked if you do, but I am happy to do that," Booker said. "There is a saying in my neighborhood that you are dipping into the Kool-Aid and you don’t even know the flavor!"

Rep. Tulsi Gabbard brought up Harris' record as a prosecutor and told the former California attorney general she should apologize to those who "suffered under your reign."

"I’m deeply concerned about this record," Gabbard said. "There are too many examples to cite, but she put over 1,500 people in jail for marijuana violations and then laughed about it when she was asked if she ever smoked marijuana.

"She blocked evidence that would have freed an innocent man from death row until the courts forced her to do so. She kept people in prison beyond their sentences to use them as cheap labor for the state of California, and she fought to keep cash bail system in place that impacts poor people in the worst kind of way."

Harris responded by saying she was proud of her work and that she worked to "reform a system that is badly in need of reform."

When the moderators returned to Gabbard, the Hawaii representative added, "The bottom line is, when you were in a position to make a difference and an impact in these people’s lives, you did not and worse yet in the case of those who are on death row, innocent people, you actually blocked evidence from being revealed that would have freed them until you were forced to do so. There’s no excuse for that and the people who suffered under your reign as prosecutor — you owe them an apology."

On the topic of race in America, Inslee pointed out his own privilege.

"I approach this question with humility because I have not experienced what many Americans have," he said. "I've never been a black teenager pulled over in a white neighborhood. I've never been a woman talked over in a meeting. I've never been an LGBTQ member subject to a slur. And so I have believed I have an added responsibility, a double responsibility to deal with racial disparity."

Gillibrand later spoke similarly, saying it shouldn't be only on people of color to stand up against racism. "I think as a white woman of privilege who is a U.S. senator running for president of the United States, it is also my responsibility to lift up those voices that aren’t being listened to," she said.

She added that she believes she is the candidate who can explain this to "white women in the suburbs who voted for Trump."

Gillibrand said: "When their son is walking down a street with a bag of M&Ms in his pocket wearing a hoodie, his whiteness is what protects him from not being shot. When their child has a car that breaks down and he knocks on someone’s door for help and the door opens and the help is given, it’s his whiteness that protects him from being shot."

Gillibrand directly questioned Biden about an op-ed he wrote in 1981, in which he had positioned himself against a child care tax credit.

"He wrote an op-ed that he believed that women working outside the home would 'create the deterioration of family.' He also said that women who were working outside the home were 'avoiding responsibility,'" Gillibrand said.

Biden responded: "That was a long time ago and here's what it's about. It would have given people making today $100,000 a year a tax break for child care. I didn’t want that. I wanted the child care to go to people making less than $100,000. And that’s what it was about. As a single father who, in fact, raised three children for five years by myself, I have some idea of what it costs. I support making sure that every single solitary person needing child care gets an $8,000 tax credit now."

When Gillibrand pressed on what he meant by "the deterioration of family," he turned to her and said she had previously shown support for his advocacy for women and now changed her mind on that, saying, "I don’t know what happened, except that you’re running for president."

That's when Harris took the chance to say that Biden has changed his mind before, too, like on the Hyde Amendment, which ensures that federal money cannot be used for abortions.

"You made a decision for years to withhold resources to poor women to have access to reproductive health care, including women who were the victims of rape and incest. Do you now say that you have evolved and you regret that?" she asked.

Biden said, "I wrote the legislation making sure that every single woman would, in fact, have an opportunity to have health care paid for by the federal government, everyone." He added: "I support a woman's right to choose."