7 standout moments from the third Democratic debate in Houston

One of the biggest clashes of the night was between former Vice President Joe Biden and former HUD Secretary Julian Castro, who served in former President Barack Obama's administration together.

Castro argued that while his plan would automatically enroll people who didn't have private insurance into a public option when they lost their jobs, for example, Biden's would require people to actively enroll.

"The difference between what I support and what you support is that you require them to opt-in, and I do not require them to opt in," Castro said. "Barack Obama's vision was not to leave 10 million people uncovered, he wanted every single person in this country to be covered."

Biden argued that people would not have to buy in to Medicare under his plan, but Castro pushed back, saying, "You just said two minutes ago that people would have to buy in — are you forgetting already what you said two minutes ago?" We need a system that automatically enrolls people no matter what," Castro said.

I'm fulfilling the legacy of Barack Obama and you're not," Castro told Biden, to which Biden shot back, "That'll be a surprise to him."

On the issue of immigration, Castro further accused Biden of constantly name-dropping Obama while shying away from the more controversial parts of Obama's record on immigration.

Mayor Pete Buttigieg and Sen. Amy Klobuchar had otherwise unremarkable nights on the debate stage, but did get in some digs at their opponents.

"This is why presidential debates have become unwatchable, this reminds people of what they cannot stand about Washington; people scoring points at each other, people poking at each other," Buttigieg said after Castro and Biden's spat.

"A house divided cannot stand," Klobuchar further admonished, quoting Abraham Lincoln.

"The bottom line is this: Donald Trump, in office on trade policy, you know, he reminds me of that guy in 'The Wizard of Oz,' you know, when you pull back the curtain, it's a really small dude," Sen. Kamala Harris said to laughter.

She also jokingly clarified that she wasn't talking about moderator George Stephanopoulos, who is known for — in addition to many aspects of a distinguished career in politics and journalism — his short stature.

Kamala Harris: "The bottom line is this: Donald Trump, in office on trade policy, you know, he reminds me of that guy in "The Wizard of Oz," you know, when you pull back the curtain, it's a really small dude?" pic.twitter.com/jxNtJLGlZf

— Axios (@axios) September 13, 2019

"Let me be very clear, anyone who does what Maduro does is a vicious tryrant," Sen. Bernie Sanders said, a much stronger denunciation of Maduro than his previous comments.

Ramos also challenged Sanders to explain the difference between Maduro's left-wing authoritarianism and Sanders' vision of Democratic socialism.

"To equate what goes on in Venezuela with what I believe is extremely unfair," Sanders said. "I'll tell you agree with what goes on in Canada and in Scandinavia — guaranteeing health care to all people as a human right," he said. "I believe the United States should not be the only major country not to offer paid family leave or medical leave."

Here's the moment where Biden made an outdated suggestion for parents to keep record players on to help kids learn, before immediately switching to talk about American involvement in Venezuela:

“We bring social workers into homes with parents to help them deal with how to raise their children...they don’t know quite what to do...Make sure you have the record player on at night.” - @JoeBiden pic.twitter.com/w3Wc6rGrh4 #maga #DemDebate

— Matt Batzel (@MattBatzel) September 13, 2019

Buttigieg made history by using a presidential debate stage to candidly discuss his decision to come out at the risk of his career, saying, "I was not interested in not knowing what it was like to be in love any longer."

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Pete Buttigieg reflects on his decision to come out and the challenges of being a "military officer serving under 'don't ask, don't tell,'" and being "an elected official in the state of Indiana when Mike Pence was governor" https://t.co/T37EaVOvlU #DemDebate pic.twitter.com/DBDMKMPvSH

— ABC News Politics (@ABCPolitics) September 13, 2019