Julian Castro, the leader of the decriminalization faction, accused fellow Democrats like Biden of “taking the bait” on Republican talking points.

“Mr. Vice President, it looks like one of us has learned the lessons of the past and one of us hasn’t,” Castro said, one of a number of attempts to portray the former vice president as out of touch with current times.

Biden said Castro’s plan to decriminalize illegal border crossings “doesn’t make sense” and argued that it would make it difficult to say no to any immigrant who wanted to avoid the delays in legal immigration.

And Biden suggested that Castro hadn’t made that argument when he was part of the Obama administration. “I don’t remember him talking about any of this when he was secretary” of Housing and Urban Development in the same Cabinet, he said.

But then, Bill de Blasio turned that argument around on Biden.

“I was vice president. I was not the president,” Biden said, noting that his conversations with former President Barack Obama were private.

“You can’t have it both ways,” Cory Booker interjected. “You invoke President Obama more than anybody in this campaign. You can’t do it when it’s convenient and then dodge it when it’s not.”

The question of decriminalization remained the major flash point separating the Democratic party’s moderates and liberals. Biden, along with Michael Bennet, defended criminal penalties as part of a comprehensive reform plan that would include a path to citizenship and legal status for those who come to the country as children.

But others, like Castro and Kamala Harris, said criminal laws have enabled President Donald Trump’s policy of separating parents from their children at the border.

“The policies of this administration have been facilitated by laws on the books that treat them as if they’ve committed crimes,” Harris said. “These children have not committed crimes.”

Bennet responded, “There is not a single person on this stage who would ever separate a parent from their child on the border.”

Harris pushed to put Biden on the defensive from the start of the debate as candidates battled over their health care plans.

Harris was laser-focused on dismantling Biden’s proposal, returning to it even when asked to respond to other candidates’ criticisms of her plan.

“In 2019 in America for a Democrat to be running for president with a plan that does not cover everyone in America I think is without excuse,” the California senator said of the former vice president’s proposal, which would add a public option to the existing Affordable Care Act system but would not necessarily give health insurance to all Americans.

Biden, seeking to rebound from a weak performance in his first debate, held his own, lighting into Harris about what he said was muddying her message on health care and offering a proposal that would take a decade to be implemented.

“The senator’s had several plans so far,” he said. “You can’t beat President Trump with double talk.”

As the candidates greeted one another on stage before the debate began, Biden shook hands with Harris and pleaded with her, “Go easy on me, kid.”

The quip signaled that he was worried she would repeat her attacks in the first debate in late June, which caught him off guard.

On health care, Harris said she had changed her plan because she’s spent months “listening to American families, listening to experts, listening to health care providers, and what I came away with is a very clear understanding that I needed to create a plan that was responsive to the needs of the American people.”

A handful of candidates, including Bill de Blasio and Tulsi Gabbard, who support Medicare for All, attempted to attack both leading candidates from the left, saying that Biden and Harris’s plans would continue to enrich insurance companies and burden Americans.

“I don’t know why Democrats on this stage are fear-mongering,” de Blasio said.

Biden took the stage under intense pressure to deliver after a rough showing in June’s debate, when he was unprepared for attacks and appeared to lose his train of thought. He and his team have said he’s ready to answer challenges to his record and to fight back any character attacks.

For weeks, he’s been battling the candidates who are flanking him at center stage — Harris to his left and Cory Booker to his right — on criminal justice, school desegregation and health care. Other candidates on stage, many averaging just 1% or 2% in polls, were poised to try to score points at Biden’s expense.

Harris got a bounce in the polls after she attacked Biden’s record on busing in the 1970s during the June debate. Since then, her numbers have slipped and she has reason to try to recover lost ground.

While Biden enjoys a big lead in polls of all Democrats, he has an even bigger edge with black voters. Cutting into that advantage will be key to the viability of Harris’s and Booker’s campaigns.

The other seven candidates along the wings of the stage may also have reason to go on the offensive against Biden, Harris or one another. The eligibility criteria for September’s debate are tighter, meaning that lower-polling candidates will need to juice their scores and fundraising to keep their campaigns alive. Those candidates include Julian Castro, Gabbard and Jay Inslee.

Tuesday’s debate put the party’s ideological divides on full display. Bernie Sanders and Elizabeth Warren faced attacks from moderates including Steve Bullock, John Delaney, John Hickenlooper and Tim Ryan on their promises for change, including Medicare for All and the Green New Deal.

With Biden as the headliner in Wednesday’s sequel, the dynamic could be reversed. He will have to defend his more conservative positions against a brand of progressivism brought by Warren and Sanders. The two firebrands could have some like-minded candidates on Wednesday’s debate stage who believe Biden’s plans to improve the Affordable Care Act and introduce new climate protections do not go far enough.

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