DETROIT —Former vice president Joe Biden, the front-runner in the race for the Democratic presidential nomination, faced down a barrage of criticism Wednesday night as his opponents sought to cast him as a relic of a bygone era, ill-equipped to lead his party as it grapples with urgent questions about race, immigration, and the best way to beat President Trump.
One by one they dug in, denigrating Biden’s health care plan, criminal justice record, support for free trade policies, and the immigration policies pursued by President Barack Obama. The attacks underscored a new willingness to lay into the record of the popular former president in order to bruise Biden, whose connection to Obama is central to his political appeal.
“You invoke President Obama more than anybody in this campaign,” said New Jersey Senator Cory Booker during a tense exchange over the rate of deportations during the previous administration. “You can’t do it when it’s convenient and dodge it when it’s not.”
But following his halting performance at the first debate, Biden sought to launch himself into the fray, attacking several of his opponents in an effort to swat away doubts about his ability to defend himself under fire, and make a forceful case for his brand of Democratic centrism in a crowded presidential field that has been pulled to the left by populist liberals.
“I have the guts to say his plan doesn’t make any sense,” Biden said, referring to a proposal by Julian Castro to decriminalize crossing the border illegally, which has become a major flashpoint over the first two rounds of Democratic debates.
And, although Harris’ surgical attack on Biden’s record on race at the first debate was the strongest moment of her campaign so far, she found herself on the defense several times Wednesday night. A more energetic Biden slammed her record as a prosecutor and her new proposal to gradually implement a Medicare for All plan over 10 years, saying she was engaging in “double talk.”
“The senator has had several plans so far,” Biden said, dismissively, “And any time someone tells you you’re going to get something good in 10 years, you should wonder why it takes 10 years.”
Yet, even though Biden tried to control the night with his own attacks, the debate highlighted that he is a frontrunner with many vulnerabilities and a passel of opponents eager to point them out in exacting detail. Because of that, any path he might carve to the nomination is likely to be a bumpy one.
With five candidates of color onstage, the second night of back-to-back debates represented the most diverse group of presidential contenders in American political history, and at times it morphed into a clash over who is best positioned to be the Democrats’ standard-bearer as the party prepares to take on an incumbent president who frequently denigrates immigrants, majority-black cities like Baltimore, and lawmakers of color.
For months, Biden has hovered in polling above the rest of the field, buoyed by his strong support from older voters of color. Harris and Booker tried to cut into Biden’s support with that group by casting themselves as leaders who can bring the Democratic Party into the future by electrifying a new and diverse coalition of voters — a point that is particularly resonant in Detroit, a majority-black city where tens of thousands of voters sat out the 2016 election in a state that Trump won by fewer than 11,000 votes.
As Biden walked on stage, he shook hands with Harris and made a joking plea: “Go easy on me, kid.”
But soon enough, Booker and Harris laid into him, extending weeks-long attacks they have used to cast him as short-sighted or insensitive on matters of race — and, perhaps, to cut into the steady support he has from older black voters, who will be key to nomination.
“Everybody’s talking about how terrible I am on these issues,” Biden said, before evoking the nation’s first black president, as he often does. “Barack Obama knew exactly who I was.”
Harris returned to the attack that turbocharged her own campaign by highlighting Biden’s willingness to work with segregationists to oppose federally mandated busing.
“Had those segregationists had their way, I would not be a member of the US Senate, Cory Booker would not have been in the US Senate, and President Obama would not have been in a position to nominate him to the position that he now holds,” Harris said.
Where Biden faltered in the first debate, trailing off as he tried to elaborate on his civil rights record, he hit back at Harris on Wednesday, denigrating her record as a prosecutor.
“When Senator Harris was the attorney general for eight years in the state of California, there were two of the most segregated school districts in the country, in Los Angeles and in San Francisco,” he said. “”I didn’t see a single solitary time she brought a case against them to desegregate.”
Tulsi Gabbard, the Hawaii congresswoman, laid into Harris on the same topic — showing how Harris’s recent rise in the polls has made her a target for candidates seeking to put progressive critiques of her record on full display. Gabbard said she had jailed people for marijuana violations and blocked evidence that would have freed a prisoner on death row.
“The bottom line is, Senator Harris, when you were in a position to make a difference and an impact in these people’s lives you did not,” Gabbard said.
Harris responded by saying she had long been deeply opposed to the death penalty and had worked hard to overhaul the system.
“As the elected attorney general of California, I did the work of significantly reforming the criminal justice system of a state of 40 million people that became a model,” Harris said.
Biden also tangled with Booker, saying that, as mayor of Newark, the New Jersey senator had presided over a police department that was investigated by the Justice Department and found to disproportionately stop black men.
“In 2007, you became mayor and you had a police department and you went out and hired Rudy Giuliani’s guy and engaged in stop and frisk,” Biden said, referring to the former Republican mayor of New York who is now a key member of Trump’s inner circle.
“You want to compare records, and frankly I’m shocked that you do, I am happy to do that,” Booker said, before turning to the 1994 crime bill that Biden helped pass.
“There are people right now in prison for life, for drug offenses, because you stood up and used that tough-on-crime phony rhetoric that got a lot of people elected but destroyed a lot of communities like mine,” Booker said. “This isn’t about the past sir, this is about the present right now.”
The candidates onstage seemed to be battling their own ghosts as much as they were each other. As Biden tried to concisely defend himself, he stumbled over his words at times and occasionally made slapdash appeals to the audience — “Google 1,000 prisoners Kamala Harris,” he implored viewers at one point.
Harris immediately launched into the details of her health care proposal, as if she were trying to bat away months of criticism that she has lacked clear answers to policy questions on the trail.
That touched off an extended debate over health care, securing the issue’s status as one of the key dividing lines of the primary after the 10 candidates who debated on Tuesday jousted over Vermont Senator Bernie Sanders’ Medicare for All plan.
On Wednesday, Biden said Harris’s plan would raise taxes on middle class Americans, while Harris accused the former vice president of leaving millions without insurance on his more modest plan.
“In 2019 in America for a Democrat to be running for president with a plan that does not cover everyone, I think it’s without excuse,” Harris said.
Several candidates pushed Biden on the ropes on the issue of immigration, with New York Mayor Bill de Blasio repeatedly asking him whether he attempted to prevent the hundreds of thousands of deportations that took place under Obama. Biden defended Obama, saying he wanted to pass comprehensive immigration reform and helped young undocumented immigrants get work permits.
“To compare him to Donald Trump I think is absolutely bizarre,” Biden shot back. “He moved to fundamentally change the system.”
Because the Democratic National Committee set a higher polling and donation bar for candidates to qualify for the next round of debates in September, Wednesday night’s showdown was do-or-die for lower-performing candidates like Washington Governor Jay Inslee of Washington and Senators Michael Bennet of Colorado and Kirsten Gillibrand of New York.
Liz Goodwin of the Globe staff contributed to this report. Jess Bidgood can be reached at Jess.Bidgood@globe.com. Follow her on Twitter@jessbidgood