Sen. Elizabeth Warren shut down former Rep. John Delaney for focusing on "what we really can’t do and shouldn’t fight for," during Tuesday night’s Democratic Presidential debate.

The ongoing debate between Delaney and Warren underscored a major them of the debate: Whether the party should pursue big ideas that appeal to progressives, or more incremental changes that appeal to moderates.

During one exchange, Delaney blasted progressives for proposing ideas that are “dead on arrival” or that “will never happen.”

Moderator Jake Tapper directed a question at Warren asking her if she described herself a capitalist to convince voters she was a safer choice than Vermont Sen. Bernie Sanders.

"I think Democrats win when we run on real solutions not impossible promises, when we run on things that are workable not fairy tale economics," Delaney said.

Warren fired back.

“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 to applause. “I don't get it.”

Debate viewers celebrated the zinger on Twitter, suggesting Warren had ended Delaney's campaign.

Contributing: John Fritze and Sarah Elbeshbishi, USA TODAY