MIAMI (Reuters) - The front-runners of the crowded Democratic presidential contest jostled on Thursday night over issues of race relations and whether the time had come for a new generation of leaders.

Former Vice President Joe Biden speaks as Democratic U.S. 2020 election presidential candidates entrepreneur Andrew Yang, South Bend Mayor Pete Buttigieg, Senator Bernie Sanders and Senator Kamala Harris listen during the second night of the first Democratic presidential candidates debate in Miami, Florida, U.S. June 27, 2019. REUTERS/Mike Segar

In heated exchanges on the second night of the primary’s first head-to-head debates, lesser-known candidates trained their fire at former Vice President Joe Biden and prominent U.S. senators engaged in shouting matches. Here are some highlights from the debate.

‘FOOD FIGHT’

Biden, the race’s front-runner, took the heat of the night’s first fiery exchange.

Eric Swalwell, a 38-year-old congressman from California, labeled Biden a relic of the party’s past by genially recalling an event he attended as a child, when Biden told a Democratic audience the time had come to pass the torch to the next generation.

Swalwell said that time had come again to solve the problems dominating the party’s debates today: climate change, student loan debt and technological advancement.

“Joe Biden was right when he said it was time to pass the torch to a new generation of Americans 32 years ago,” he said. “He’s still right today.”

Biden smiled broadly as he responded to laughter from the audience: “I’m still holding onto that torch.”

The exchange triggered a melee, with several of the other eight candidates raising their voices to inject the last word.

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Senator Kamala Harris of California silenced the shouting with a memorable one-liner: “America does not want to witness a food fight. They want to know how we’re going to put food on their table.”

RACIAL FAULT LINES

The party’s rapidly shifting equilibrium on issues of race led to another dramatic exchange between Biden and Harris, who would be the first black female nominee for president.

She called out Biden for recently speaking with fondness about a past political era when he could collaborate with pro-segregationists when he was in the U.S. Senate decades ago.

“It’s personal and it was hurtful to hear you,” she told Biden, noting the party needed more than “intellectual debate” about the nation’s ongoing racial disparities.

“I do not believe you are a racist,” she told Biden, but still pressed him over past opposition to school busing plans that aimed to end racial segregation in schools.

Visibly rattled, Biden was terse as he defended his record.

“It’s a mischaracterization of my position across the board: I did not praise racists. That is not true,” he said. “If we want to have this campaign litigated on who supports civil rights and whether I did or not, I’m happy to do that.”

HANDS UP?

Debate moderators used an old-school approach to test the policy differences in the long row of candidates, asking for a collective show of hands to see who agreed on tricky positions.

All 10 raised their hands to show their healthcare plans would provide medical services for undocumented immigrants.

But only two - Harris and fellow Senator Bernie Sanders of Vermont - signaled agreement for eliminating the nation’s current private insurance system in favor of government-run healthcare for all.

Earlier in the evening, moderators pushed Sanders on whether the financing for such a plan would mean higher taxes.

“Yes, they will pay more in taxes but less in healthcare for what they get,” he said in the second round of questioning seeking his direct answer.