Joe Biden battled Bernie Sanders and Elizabeth Warren on health care in a fight emblematic of the Democratic Party’s deepest schism ahead of next year's presidential election.
The struggle between the Democrats’ left wing and a faction of moderates over whether to promote a sweeping government-run health care plan or to build on Obamacare dominated the third Democratic debate, the first in which all 10 of the leading candidates shared the same stage.
But other differences between former vice president Biden and his two chief rivals were more muted during the rest of the two-and-a-half-hour event, which had been particularly anticipated for the potential of a Biden-Warren face-off. Lower-polling candidates made occasional efforts to break out but were largely unable to deliver on their attempts to needle the trio of septuagenarians at centre stage.
Biden repeatedly claimed the mantle of former president Barack Obama’s de facto successor, as he did when he attacked Ms Warren’s embrace of Mr Sanders’ Medicaid for All healthcare plan.
“I know the senator says she’s for Bernie but I’m for Barack,” Mr Biden said, arguing for improvements to Obamacare rather than the government takeover of health insurance advocated by Mr Sanders and Ms Warren.
The most aggressive attempt to cut down the front-runner came from his former Obama administration colleague Julian Castro. He asserted his healthcare plan was better than Mr Biden’s because people who qualified would automatically be enrolled, saying that they would have to opt in to Mr Biden’s Medicare for Choice plan.
“They wouldn’t have a buy in,” Mr Castro said.
When Mr Biden shot back, “They do not have to buy in,” Mr Castro pounced.
“Are you forgetting what you said two minutes ago?” he said. “You’re forgetting that?”
But Mr Biden had said earlier that people who cannot afford insurance would be “automatically enrolled in the Medicare-type option that we have.”
Mr Castro’s not-so-subtle attack on Mr Biden’s memory exposed what had been a largely unspoken question in the Democratic field: whether the 76-year-old has the energy and endurance to fight a campaign against President Donald Trump.
At that point, other Democrats made an appeal to unity. “This is why debates have become unwatchable,” Pete Buttigieg said. “We’re all on the same team,” Andrew Yang said.
“We’ve got one shot to make Donald Trump a one-term president,” Cory Booker said. “And we can’t lose it by the way we talk to each other.”
But Mr Biden fought on for the rest of the debate, even defying moderators who tried to cut him off toward the end. “No, I’m going to go like the rest of them do, twice over, OK?”
Despite the occasional rancour, the Democrats also made more of an attempt to unify on two things they agreed on: praising Obama and condemning Trump.
Party officials recently have been warning against criticising the former president at risk of turning off voters and instead focus on Mr Trump.
Trade brought a full round of criticism of the current president. The candidates who responded to questions on trade all agreed that Trump’s approach to trade – especially his erratic approach to negotiations with China -- isn’t working, but did not offer detailed solutions.
Mr Biden, Mr Sanders and Ms Warren all agreed that labour, farmers and environmentalists should be at the table for future trade talks.
“We can use trade not to undermine American workers”, farmers or small businesses but to “help build a stronger economy”, Ms Warren said, also bemoaning the role that she said corporate interests have had in recent trade talks. Over the last two decades, trade has been the fourth-biggest issue for Washington lobbyists, according to the Centre for Responsive Politics.
Mr Sanders noted his opposition to the North American Free Trade Accord and permanent normal trade relations with China, both measures that Mr Biden had voted for while serving in the Senate. But Mr Biden reiterated the plan for China trade talks that he has also mentioned on the campaign trail, that the US should “organise the world to take on China”.
The candidates clashed again over gun control. Mr Biden has said Kamala Harris’ proposal to ban assault weapons by executive order would be unconstitutional.
“Hey Joe, instead of saying no we can’t, let’s say yes we can,” Senator Harris said, echoing Mr Obama’s slogan.
“Let’s be constitutional. We’ve got a constitution,” Mr Biden interjected.
Moderators asked pointed questions to the two former prosecutors on the stage, Ms Harris and Amy Klobuchar, about their records prosecuting drug crimes and supporting police.
Ms Harris said there were “distortions” of her record and that she tried to reform the system from the inside. “I was born knowing about how this criminal justice system in America has worked in a way that is informed by racial bias,” she said.
Ms Klobuchar emphasised her work with the Innocence Project, and of prosecuting violent criminals accused of shooting schoolchildren in minority neighborhoods.
Mr Biden also tried to establish a position as a reformer. “Nobody should be in jail for a non-violent crime,” he said. A campaign aide later clarified that he was talking only about non-violent drug crimes.
The debates so far have not altered the trajectory of the contest, leaving Mr Biden in the lead of national polls and Ms Warren and Mr Sanders in a struggle for second. After a brief surge following the first debate, Ms Harris’s poll numbers have flatlined, leaving her a distant fourth.
Mr Biden is four points lower than he was before the first debate, but maintains a 10-point buffer with Ms Warren and Mr Sanders in the RealClearPolitics average.
Democrats chose Houston as the venue for the debate to highlight their chances of winning the state for the first time since Jimmy Carter did it in 1976. But the debate showed they still remain divided on what will bring voters to their side.