HOUSTON (WABC) -- The three leading Democratic presidential candidates clashed over health care, along with immigration and President Barack Obama's legacy in a fierce debate Thursday night that pitted an aggressive Joe Biden against liberal rivals Elizabeth Warren and Bernie Sanders.
"This is America," said Biden, his party's early front-runner, before calling Sanders "a socialist." ''I stand with Barack Obama all eight years, good bad and indifferent."
The top White House hopefuls faced off for the first time alongside seven other candidates who are under increasing pressure to break out of the pack. All assailed Trump without mercy.
New Jersey Sen. Cory Booker called Trump a racist. Former Texas Rep. Beto O'Rourke called him a white supremacist. And Kamala Harris, a California senator, said Trump's hateful social media messages provided "the ammunition" for recent mass shootings.
"President Trump, you have spent the last two-and-a-half years full time trying to sow hate and vision among us, and that's why we've gotten nothing done," Harris declared.
Sanders said Biden, Obama's two-term vice president, bears responsibility for millions of Americans going bankrupt under the "Obamacare" health care system.
Biden slapped back at both Sanders and Warren and contended they haven't yet explained how they would pay for Sanders' government-backed "Medicare for All" health care plan.
Warren and Sanders defended their plan, saying the middle class won't pay more.
"How do we pay for it? We pay for 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," said Warren.
One of the biggest moments came exactly one hour in when O'Rourke, who lives in El Paso, was asked if he was really in favor of confiscating guns.
"Hell yes, we're going to take away your AR-15, your AK-47," he said, "We're not going to allow it be to be used against a fellow American anymore."
Early in the debate Biden's closest competitors didn't attack the frontrunner but Julian Castro certainly did.
"Every time something good about Barack Obama comes up he says Oh I was there. I was there, that's me too," said Castro. "And then every time somebody questions part of the administration that we were both part of, he says, well that was the President."
Castro, who served as Obama's housing chief, kept the pressure on the front-runner.
The 44-year-old Texan appeared to touch on concerns about Biden's age when he accused the former vice president of forgetting a detail about his own health care plan. At 76, Biden would be the oldest president ever elected to a first term.
"Are you forgetting what you said two minutes ago?" Castro asked. "I can't believe that you said two minutes ago that you have to buy in and now you're forgetting that."
He added: "I'm fulfilling the legacy of Barack Obama and you're not."
The ABC News debate was the first limited to one night after several candidates dropped out and others failed to meet new qualification standards. A handful more candidates qualified for next month's debate, which will again be divided over two nights
Earlier this year, prior to the first Democratic debates, the DNC announced more stringent qualifying rules for the fall debates in September and October.
In order to qualify for the September debate, candidates needed to cross both the polling and grassroots funding thresholds. Candidates must have received 2% or more support in at least four national polls or polls conducted in the early-voting states of Iowa, New Hampshire, South Carolina and/or Nevada and have been publicly released between June 28 and August 28.
Any candidates' four qualifying polls must have been sponsored by one or more of the following organizations approved by the DNC: The Associated Press, ABC News, CBS News, CNN, the Des Moines Register, Fox News, Monmouth University, NBC News, The New York Times, National Public Radio, Quinnipiac University, University of New Hampshire, The Wall Street Journal, USA Today, the Washington Post and Winthrop University. They also needed to be conducted by different organizations or -- if by the same organization -- had to be in different geographical areas.
Candidates also needed to receive donations from at least 130,000 unique donors over the course of the election cycle, with a minimum of 400 unique donors per state in at least 20 states. Qualifying donations must have been received by 11:59 p.m. on Aug. 28 for the September debate.
(The Associated Press contributed to this report.)
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Candidates face off in third Democratic debate on ABC