HOUSTON - Former Vice President Joe Biden launched into an aggressive defense of his health-care proposal Thursday by attacking the more expensive and ambitious Medicare-for-all program backed by his top rivals in the Democratic race during a debate that started with themes of unity but quickly devolved into clashes over sharp policy differences.
Biden, flanked by Sen. Elizabeth Warren, D-Mass., and Sen. Bernie Sanders, I-Vt., began the debate by going on offense against the two liberal candidates, casting their universal health-care program as unworkable, too expensive and a betrayal of President Barack Obama's signature achievement.
"I know the senator says 'I'm for Bernie'," Biden said, turning toward Warren. "Well I'm for Barack."
Biden stressed that he wants to expand on the Affordable Care Act, commonly known as Obamacare, rather than replace it with Medicare-for-all, which is estimated to cost more than $30 trillion over 10 years.
He called Sanders a "socialist," and questioned the amount of time it would take to pass his more far-reaching plan. "Do something now!" Biden shouted.
"How are we going to pay for it?" Biden asked. "This is about candor. Honesty. Big ideas."
The debate quickly developed as a virtual battle over the soul of the Democratic Party, including key questions of whether the party should pursue policies of sweeping change or a more incremental return to normalcy in the wake of President Donald Trump.
Sanders and Warren largely joined forces to spar with Biden early in the race, casting their plans as more properly suited to the major problems of the day.
Several candidates also tried to balance offering praise of Obama with giving themselves space to criticize Biden, who served as Obama's vice president for eight years.
Warren said that "we all owe a huge debt to President Obama" and tried to frame Medicare-for-all as an improvement on Obamacare.
Pressed on whether middle-class families would see a tax hike to fund the program, Warren dodged the question. "Middle-class families are going to pay less," she said, focusing on overall costs.
Sanders, whose voice was hoarse, also said that families are looking for "effective" health care.
While several candidates said they wanted to unify the country, they did not pull punches in drawing contrasts with one another.
"I don't think it's a bold idea, I think it's a bad idea," Sen. Amy Klobuchar of Minnesota said of Sanders' health-care bill.
"Are you forgetting what you said two minutes ago?" former San Antonio mayor Julián Castro asked Biden, seeming to allude to questions about the 76-year-old's age and mental acuity.
"I'm fulfilling the legacy of Barack Obama and you're not," Castro said to Biden, arguing that the vice president's health-care plan did not provide universal coverage.
Biden shot back: "That'll be a surprise to him."
It was one of several zingers of the night, with Biden - who had been on the receiving end of many attacks during the first two rounds of debates - often the aggressor.
"For a socialist, you've got a lot more confidence in corporate America than I have," Biden said to Sanders, scoffing at the idea that companies would pay workers more if they had fewer health-care costs.
The third debate came at an inflection point in the race, with a narrowing of the field that has started to clarify the campaign as it heads into the fall. The trio at the center of the stage - Biden, Sanders and Warren - have consistently held the top places in the polls, with the rest of the candidates trailing far behind and growing increasingly desperate.
Biden and his allies have been attempting to cast his record as one that liberals in the party should be proud of and one that is more realistic than the more far-reaching promises offered by Warren and Sanders. They have also attempted to portray Warren as hypocritical for raising money from big donors up until this year during her presidential campaign.
In the early portions of the debate, multiple candidates spoke highly of Obama and his role in shepherding through an expansive health-care plan. Obama has opted not to endorse any candidate in the primary.
Before the debate Thursday morning, Biden released a video touting working together with Obama in the White House.
"Barack Obama was a great president," Biden wrote on Twitter. "We don't say that enough."
Former congressman Beto O'Rourke was in his home state, the place where he narrowly lost to Sen. Ted Cruz, R-Texas, last November. He has tried to refocus his campaign by orienting it more toward running against Trump. In the wake of a mass shooting in his hometown of El Paso, he has also proposed more aggressive gun-control measures and, in channeling some of the moral outrage, has gone back to using expletives on the campaign trail. Candidates were warned ahead of the debate to avoid "foul language."
Trump, who spent Thursday evening at a House Republican retreat in Baltimore, loomed large on the debate stage as Democrats pilloried his policies and his behavior in office.
"Houston, we have a problem," Klobuchar said, invoking Trump. "We have a guy there who is literally running our country like a game show. He would rather lie than lead."
"And now, President Trump, you can go back to watching Fox News," Sen. Kamala Harris of California said at the end of her opening remarks, which she dedicated to attacking the president for "trying to sow hate and division."
"The most dangerous president in the history of this country," Sanders said of Trump.
O'Rourke called Trump a "white supremacist" and accused him of inspiring the gunman who traveled to El Paso, Texas, and killed 22 people in August. The White House has called such accusations disingenuous.
Trump campaign officials hosted an event for Hispanic voters in Houston and took out ads in the Houston Chronicle attacking Democrats on issues including taxes, energy and health care.
Before the debate, a plane funded by the Trump campaign circled above Houston with a banner that read: "SOCIALISM WILL KILL HOUSTON'S ECONOMY! VOTE TRUMP 2020"
A Washington Post-ABC News poll released this week showed Trump trailing Biden, Warren, Sanders and Harris by significant margins in a general election.
Trump has disputed the poll's accuracy. Speaking to reporters before the debate Thursday, Trump said he expected Biden, Warren or Sanders to win the Democratic nomination. He said he would not be watching the debate live, because it coincided with his visit to the House Republican retreat in Baltimore.
"I'm going to have to watch it as a rerun," he said.
Thursday's debate marked the third round of 12 scheduled Democratic debates, and the first in which a large portion of the declared candidates did not qualify. Several candidates who failed to meet minimum polling and donor targets set by the Democratic National Committee were kept off the stage.
Some of those candidates, including self-help author Marianne Williamson and Rep. Tulsi Gabbard of Hawaii, are within striking distance of qualifying for the next round of debates next month.