The first night of the second round of debates between Democrat contenders for the US presidency has concluded in Detroit, Michigan.
US Democratic presidential nominees have met in Detroit, Michigan for the first of two nights of debate to determine who will face off against Republican President Donald Trump in the 2020 election.
Standing side by side at centre stage on Tuesday night, Bernie Sanders and Elizabeth Warren slapped back against their more cautious rivals who ridiculed Medicare for All and warned that "wish-list economics" would jeopardise Democrats' chances for taking the White House next year.
"I don't understand why anybody goes to all the trouble of running for president of the United States just to talk about what we really can't do and shouldn't fight for," said Warren, a Massachusetts senator, decrying Democratic "spinelessness".
Sanders, a Vermont senator, agreed: "I get a little bit tired of Democrats afraid of big ideas."
A full six months before the first votes are cast, the tug-of-war over the future of the party pits pragmatism against ideological purity as voters navigate a crowded Democratic field divided by age, race, sex and ideology.
The fight with the political left was the dominant subplot on the first night of the second round of Democratic debates, which was notable as much for its tension as its substance.
Twenty candidates are spread evenly over two nights of debates on Tuesday and Wednesday.
The second night features early front-runner Joe Biden, the former vice president, as well as Kamala Harris, a California senator.
While much of the debate was dominated by attacks on the preferred liberal health care policy, the issue of race emerged in the second hour.
The candidates were unified in turning their anger toward Trump for using race as a central theme in his re-election campaign. Sanders called Trump a racist, while others said the president's rhetoric revived memories of the worst in the country's history, including slavery.
The marathon presidential primary season won't formally end for another year, but there was an increasing sense of urgency for many candidates who are fighting for survival.
More than a dozen could be blocked from the next round of debates - and effectively pushed out of the race - if they fail to reach new polling and fundraising thresholds implemented by the Democratic National Committee.
While he avoided any direct confrontations with his more liberal rivals, Pete Buttigieg tried several times to present himself as the more sober alternative in the race. He rejected extreme positions, quoted scripture and abstained from calling out his opponents.
The 37-year-old mayor of South Bend, Indiana, also subtly emphasised the generational difference between himself and Sanders, the candidate 40 years his senior standing to his side.
In targeting Medicare for All, the more moderate candidates consistently sought to undermine Sanders and Warren.
Yet Sanders and Warren did not back down. While they are competing for the same set of liberal voters, there seemed to be no daylight between them.
"Health care is a human right, not a privilege. I believe that. I will fight for that," Sanders said.
A new set of candidates, none with more to lose than Biden, will face off on Wednesday.