At the Democratic presidential debate on Tuesday night, John Delaney argued that some of his more left-wing opponents’ proposals simply weren’t workable.

Elizabeth Warren wasn’t having it.

Delaney was one of several centrists on the stage who took on Sens. Warren and Bernie Sanders, arguing that their health care and economic policies were too radical to win over American voters in a race against President Trump.

At one point, Warren struck out for idealism: “We can’t choose a candidate we don’t believe in just because we’re too scared to do anything else.” Moderator Jake Tapper asked Delaney to respond.

“Democrats win when we run on real solutions, not impossible promises,” the former Congress member said, “when we run on things that are workable, not fairy tale economics.”

He added that Detroit, where the debate took place, is “turning around because the government and the private sector are working well together. That has to be our model going forward.”

For Warren, his attitude was defeatist.

“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,” she said. “I don’t get it.” The audience laughed and cheered.

WARREN ethers Delaney: "I don't understand why anybody goes to all the trouble of running for president of the United States to talk about what we really can't do and shouldn't fight for." pic.twitter.com/ymDj6ggsve — Aaron Rupar (@atrupar) July 31, 2019

Warren went on to talk about corruption in Washington. “It is giant corporations that have taken our government and that are holding it by the throat,” she said, “and we need to have the courage to fight back against that, and until we’re ready to do that, it’s just more of the same.”

While last month’s debates showed candidates competing to stake out progressive positions, including arguing over who was a better defender of abortion rights, Tuesday night found some of the candidates trying to out-moderate each other. Warren’s comment felt like a rebuke to that strategy, and was a way for her to stand out from the field as someone unafraid to stake out uncompromising positions.

“I’m ready to get in this fight,” she said. “I’m ready to win this fight.”