Democratic presidential hopeful Massachusetts Senator Elizabeth Warren speaks during the fourth Democratic primary debate of the 2020 presidential campaign season co-hosted by The New York Times and CNN at Otterbein University in Westerville, Ohio on October 15, 2019.

"Costs will go up for the wealthy, for corporations," she said at the debate. "But for middle-class families, it will go down."

Warren has promised that Medicare for All would raise taxes on the wealthiest Americans and lower costs for middle-class families.

"At least Bernie's being honest here," Minnesota Sen. Amy Klobuchar said at the fourth Democratic primary debate, referring to Vermont Sen. Bernie Sanders' universal health care plan, which Warren said she supports. Sanders has acknowledged taxes would go up for the middle class under his proposal, and he did so again Tuesday.

Democratic presidential candidates tore into Sen. Elizabeth Warren on Tuesday after she dodged questions on whether middle-class Americans would have to pay more in taxes under her "Medicare for All" proposal.

A moderator followed up: "You have not specified how you're going to pay for the most expensive plan, Medicare for All. Will you raise taxes on the middle class to pay for it? Yes or no?"

Warren again avoided a direct answer to that question, prompting a sharp response from South Bend, Indiana, Mayor Pete Buttigieg.

"I don't think the American people are wrong when they say what they want is a choice," said Buttigieg, who has put forward a plan that retains private insurers, which he labels "Medicare for All who want it."

Buttigieg added: "I don't understand why you believe the only way to deliver coverage for everybody is to obliterate private plans."

Klobuchar, too, noted that Sanders has been clear that middle-class taxes will go up under Medicare for All, though he maintains that overall costs will go down.

"The difference between a plan and a pipe dream is whether it can actually get done," Klobuchar said. The Minnesota senator supports revamping the Affordable Care Act, which passed under President Barack Obama and Vice President Joe Biden, who is now a front-runner in the 2020 race.

President Donald Trump's campaign quickly sent out a response to all 12 Democrats on the Ohio debate stage.

"While the Democrats are debating Medicare for All and a 'public option,' only one fact matters: all of these proposals will kill private health insurance plans," the campaign said in a statement.