In sharp exchanges, Democrats go after front-runner Biden, Harris

Joe Biden had to fend off attacks Wednesday during a Democratic presidential primary debate about his stances on health care, immigration and criminal justice, as several Democrats trailing in the polls looked to increase their standing.

Ten candidates faced off on the stage of the Fox Theatre in Detroit, Michigan, one night after 10 other Democratic hopefuls clashed on the same stage.

US Senator Cory Booker of New Jersey, in calling out the former vice-president on favoring giving visas to "PhDs", said it was that type of division on immigration that Republicans were supporting. Booker also chastised Biden for invoking "President Obama more than anyone in this campaign".

Biden went back at Booker over his tenure as mayor of Newark, New Jersey, saying Booker hired (former New York City Republican mayor and Donald Trump adviser) "Rudy Giuliani's police chief".

Booker criticized Biden's support of a 1994 crime bill that the senator said disproportionately affected minority citizens.

"There are people right now in prison for life for drug offenses," Booker said, accusing Biden of using "phony rhetoric" in touting the crime bill. "I believe in redemption. You offered no redemption."

New York Mayor Bill de Blasio, who in his second debate again made a move to be heard over the fray, asked Biden if he had counseled former president Barack Obama against deportations of undocumented immigrants.

Biden said his conversations with the president were private.

"You still haven't answered my question," de Blasio replied.

US Senator Kamala Harris of California, who pressured Biden in the June debates by criticizing his opposition to school busing to integrate schools in the 1970s, found herself fending off attacks on her own record as California attorney general.

Biden said Harris did nothing about racial polarization in public schools in San Francisco and Los Angeles.

US Congresswoman Tulsi Gabbard of Hawaii said Harris put 1,500 people in prison for marijuana convictions and "laughed when she was asked if she smoked marijuana". Gabbard said Harris "actually blocked evidence" that would have freed a death row prisoner.

Entrepreneur Andrew Yang, whose parents came to the US from Taiwan, said the candidates should have been talking about all the jobs lost to artificial intelligence.

"We've already automated away millions of manufacturing jobs," Yang said. "Amazon is closing 30 percent of America's stores and malls and paying zero in taxes."

Earlier in the debate, Biden opposed the "Medicare for all" approach to the American healthcare system, an issue that was prominent in Tuesday's debate and favored by top-tier candidates, the senators Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts.

"You can't beat President Trump with double talk on this plan," Biden told Harris. "The plan no matter how you cut it costs $3 trillion. It will require middle-class taxes to go up, not down."

"In 2019 in America for a Democrat to be running for president with a plan that does not cover everyone, I think is without excuse," Harris countered.

"The ultimate choice is an election," de Blasio said. "This should be the party that stands for universal healthcare."

Booker, who said "we spend more than every other nation" on health care, said pitting progressives versus moderates on the issue was self-defeating.

On trade with China, Gabbard said that US tariffs on China have had a "ravaging and devastating effect" on American farmers.

Biden said he would "renegotiate" the Trans-Pacific Partnership, a proposed trade agreement from which Trump withdrew the US.

"Either China is going to write the rules on 21st century trade or we are," Biden said.

US Senator Kirsten Gillibrand of New York, when the issue of racial polarization was addressed, said: "I can explain to white women in the suburbs that when their son is walking down the street with a bag of M&Ms in his pocket, wearing a hoodie, his whiteness is what protects him from not being shot."

Also on the stage Wednesday were US Senator Michael Bennet of Colorado; Julian Castro of Texas, former secretary of Housing and Urban Development; and Washington state Governor Jay Inslee.