The two liberal senators were both front-and-centre at the debate, the first of a two-night event marking the second round of debates between the 20 leading Democratic candidates for president.
Both candidates represent some of the most progressive ideologies of the Democratic party, and are known best for their unapologetic embrace of aggressive plans to overhaul health care, higher education, child care and the economy.
Mr Sanders and Ms Warren won the night in terms of air time: the Vermont senator led the first hour with nearly six full minutes of speaking, while Ms Warren came in second with five minutes and 14 seconds. They were trailed by John Delaney, a moderate Democrat who spent the night – and much of his campaign – attacking progressive policies like the Green New Deal and Medicare for All, who had three minutes and 50 seconds of speaking time within the first hour of the debate.
Mr Sanders was in particularly animated form – told by Tim Ryan that he didn’t know that he could guarantee dental care, hearing aids and glasses for the elderly, the senator angrily retorted: “I do know, I wrote the damn bill!”
When it came to the debate stage, the real winners were the progressive policies rather than the candidates themselves. The audience cheered for the 2020 hopefuls who signed onto ambitious agendas like the Green New Deal, a massive plan to overhaul the nation’s environmental efforts and get to zero carbon emissions in the near future, as well as reparations for black communities.
Those plans may be popular among many Democrats but give Donald Trump and his Republican allies ample opportunity to cast all Democrats as extreme while they battle for the party’s nomination to challenge him in the 2020 general elections.
Ahead of the debates, CNN spoke to an anonymous source who reportedly advised Mr Sanders ahead of the event that said the senator “may draw a distinction with Elizabeth Warren … on a question of electability”. The two instead largely held together and embraced the plans that brought them to the centre of the debate stage, while calling out their more moderate counterparts.
“I don’t understand why anybody goes to all the trouble of running for president to talk about what we really can’t do,” Ms Warren said while addressing Mr Delaney’s criticism of her plans.
Mr Sanders added that he was “fed up with Democrats who are afraid of big ideas”.
Other 2020 Democrats shared bold and progressive plans that appeared to receive swift support from the crowd and online, from Pete Buttigieg’s idea of a constitutional amendment “to clear up Citizens United”, to Marianne Williamson’s long-held support for providing reparations to black Americans.
The fight for the political left was just one subplot as the first wave of 10 candidates met in Detroit.
Whether Mr Delaney’s continued attacks against his progressive counterparts will help elevate his campaign remains to be seen. But there was one clear loser: the president.
Virtually all of the Democrats on the debate stage called him out by name and attributed much of the divisiveness in American politics to Mr Trump.
Mr Sanders noted that polling showed him beating Mr Trump in a clutch of key Midwestern states because “he is a fraud and a phony”.
A second group of 10 that features early front-runner Joe Biden as well as Kamala Harris convenes on Wednesday night. The debate host, CNN, chose the groupings at random.
The Associated Press contributed to this report
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