The comments kicked off a theme that dominated the night as a group of centrist and lesser known candidates took potshots at the two most left-wing politicians on the stage.
Some of the fiercest clashes came over healthcare. Mr Sanders and Ms Warren’s willingness to force people to abandon their private insurance in favour of government-funded options was especially targeted.
“I’m not going to support any plan that rips away quality health care from individuals,” said Mr Bullock. “Why do we have to be so extreme?” asked Mr Delaney. Tim Ryan, an Ohio congressman, warned that such a policy would be interpreted as the Democrats trying to “take away” healthcare from some of the neediest.
But both candidates stood their ground. “We are the Democrats. We are not about trying to take healthcare away from anyone,” Ms Warren said, insisting such claims amounted to “using Republican talking points”.
There was similar sparring over the “Green New Deal”, a bold progressive plan for tackling climate change that in one iteration included the ambition of guaranteeing every adult American a job.
John Hickenlooper, the former governor of Colorado whose candidacy is yet to take off, said of the policy: “That is a disaster at the ballot box. You might as well FedEx the election to Donald Trump.”