Leading contenders to be the next US Democratic presidential nominee clashed on Thursday, in a debate that saw  former Vice President Joe Biden in a combative mood.

Ten hopefuls took to the stage in Houston, a tightened lineup from previous debates in June and July which featured 20 hopefuls over two nights. However, the three older contenders — who are also the favorites — provided the initial focus with a fierce debate on health care.

The more politically cautious Biden — the early frontrunner in the race — hit out at the two most prominent progressives, Elizabeth Warren and Bernie Sanders over their "Medicare for all” plan to extend government-funded health care to all Americans.

Sanders had claimed that as Obama's vice president Biden bore responsibility for millions of Americans going bankrupt under the Obamacare system.

Biden hit back by dismissing universal health care as a pipe dream with costs that had not been properly estimated. He defended his own plan, which builds on Obamacare.

"I lay out how I can pay for it, how I can get it done, and why it's better," said Biden.

Sanders, who advocates a shift away from private health insurance to a universal system, assured voters: "We will finally make sure that every American has health care as a human right, not a privilege."

Warren, an ascendant in the race, said a universal health care policy would be funded by those who could most afford it.

"Those at the very top, the richest individuals and the biggest corporations, are going to pay more. And middle-class families are going to pay less," Warren said.

Staking their claim

With the main three contenders in their seventies, it was up to the younger contenders stand out to stay relevant.

Obama-era Housing Secretary Julian Castro launched his own attacks on Biden, arguing that it was time for new solutions.

"Our problems didn't start with Donald Trump," Castro said in his opening statement. "We won't solve them by embracing old ideas."

However, those hoping to emerge from the pack saved their harshest criticism for Trump.

New Jersey Senator Cory Booker denounced the president as a racist. Former Texas Representative Beto O'Rourke called him a white supremacist. Meanwhile, California Senator Kamala Harris claimed that Trump's social media messages had provided "the ammunition" for recent mass shootings.

Several more candidates are set to join a further debate next month, which will be spread over two nights.

rc/sms (AP, Reuters, dpa, AFP)

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