Here are the 7 breakout moments from the 4th Democratic debate in Ohio

Ohio, the location of the debate, has been especially hard-hit by global trade and automation, which have devastated the auto manufacturing industry in the state.

UAW union members and employees of General Motors — which was once the top employer in Ohio – have recently been on strike for weeks.

While Sanders is advocating for a federal jobs guarantee, Yang's signature policy proposal is giving every American $1,000 a month through a universal basic income program.

Nearly every candidate argued in favor of more protections for labor unions and fairer trade deals that prioritize worker's rights.

"The data show that we have had a lot of problems with losing jobs. The reason is bad trade policy. The reason has been a bunch of giant multinational corporations who have been calling the shots on trade," Warren said.

Read more: Trade wars could slow global growth to weakest pace since financial crisis, IMF warns

One of Warren's signature campaign plans is to institute a wealth tax on the richest Americans to pay for an array of other social benefits including Medicare For All, universal childcare, and elimination of student loan debt.

"I want to give a reality check to Elizabeth. No one on this stage wants to protect billionaires. Not even the billionaire wants to protect billionaires," Klobuchar said, referring to Steyer. "We have different approaches. Your idea is not the only one."

Later, O'Rourke sniped that "sometimes Senator Warren is more about being punitive and pitting some part of the country against each other, instead of lifting people up," which Warren vehemently rebutted.

"I'm really shocked at the notion that anyone thinks I'm punitive. Look, I don't have a beef with billionaires ... I just want to make sure we're lifting up the families who are working and need help," she said.

Towards the end of the debate during a discussion over big tech, Harris took Warren to task for not joining her in agreeing that Twitter should shut down President Donald Trump's account.

Read more: Elizabeth Warren says she won't accept major donations from tech executives after vowing to break up big tech companies like Facebook, Google, and Amazon

Foreign policy took center stage for a portion of Tuesday's debate amid the backdrop of the Trump administration's sudden withdrawal of US troops from Syria.

The move gave an opening for Turkish forces to move into the area, directly threatening the existence of the Kurdish people, who have been among the US' strongest partners in the fight against ISIS, and giving the terror group an opening.

Gabbard, who served in the US Army and is currently in the Army reserves, is running on an expressly anti-interventionist platform of reducing US military presence abroad.

But when Gabbard characterized US involvement in Syria as an unnecessary "regime change war" and advocated for the US to withdraw from the region, Buttigieg firmly pushed back.

"Well, respectfully, congresswoman, I think that is dead wrong," Buttigieg said. "The slaughter going on in Syria is not a consequence of American presence, it a consequence of a withdrawal and a betrayal by this president of American allies and American values."

Read more: Pete Buttigieg and Tulsi Gabbard, the only military vets on the Democratic debate stage, duke it out over US action in Syria

A testy exchange on Donald Trump's Syria policy between Tulsi Gabbard and Pete Buttigieg. #ctl #p2 #DemocraticDebate pic.twitter.com/QuwZn3Rag3

Earlier in the week, O'Rourke and Buttigieg sniped at each other on social media over Buttigieg labeling O'Rourke's mandatory buybacks as "a shiny object" and adding, "I get it. He needs to pick a fight in order to stay relevant," of O'Rourke's plan.

The fight blew out into the open on the debate stage, where Buttigieg accused of O'Rourke of not knowing how the specifics of his plan would even work, and accusing it of distracting from more immediate and realistic solutions.

"The problem isn't the polls, the problems is the policy. I don't need lessons from you on morals political or personal. The problem is not other Democrats who don't agree with your particular idea of how to handle this. The problem is the National Rifle Association and their enablers in Congress."

In turn, O'Rourke said that Buttigieg's comments were "a slap in the face" to gun violence survivors.

Read more: Which gun control policies could prevent mass shootings, according to a gun violence expert

Pete Buttigieg and Beto O'Rourke go back and forth on gun control and buyback programs.

Buttigieg: "I don't need lessons from you on courage — political or personal." pic.twitter.com/X47jB3L1c7

In a discussion of drug policy, Booker quipped that Sanders supports medical marijuana legalization, Sanders joked, "I'm not on it tonight."

CNN anchor Erin Burnett asked Sanders, "You're 78 years old, and you just had a heart attack. How do you reassure Democratic voters that you're up to the stress of the presidency?"

After thanking supporters for the well-wishes following his heart attack, Sanders said he would show he's ready to take on the presidency at a big rally planned for this Saturday in Queens, New York.

And Biden, who would be 78 upon taking office, said that decades of experience in government and his advanced age makes him more, not less, qualified to be president.

"Look, one of the reasons I'm running is because of my age and my experience. With it comes wisdom. We need someone to take office this time around who on day one can stand on the world stage," Biden responded, also pledging to release his medical records sometime before the Iowa caucuses.

Read more: Joe Biden's former brain surgeon explains why he's not too old to be president

"I'm going to say something that is probably going to offend some people here, but I'm the only one on this stage that has gotten anything really big done from the Violence Against Women Act, to making sure that we pass the Affordable Care Act," Biden charged.

Warren was quick to hit at Biden, pointing out that she created the Consumer Financial Protection Bureau under the Obama administration.

"So you started this question with how you got something done. Following the financial crash of 2008, I had an idea for a consumer agency that would keep giant banks from cheating people."

Biden then partially took credit for the CFPB's creation, saying, "I agreed with the great job she did, and I went on the floor and got you votes. I got votes for that bill. I convinced people to vote for it, so let's get those things straight too."

In response, Warren further took a dig at Biden by crediting Obama and not him, saying, "I am deeply grateful to President Obama, who fought so hard to make sure that agency was passed into law."

Read more: Obama administration officials called Elizabeth Warren 'sanctimonious' and a 'condescending narcissist'

Here's that Biden vs. Warren exchange on the CFPB >> pic.twitter.com/NE2fPCwvZO