“Everybody who is running for president right now knows that families are getting crushed by the high cost of health care,” Warren told the crowd of nearly 500 people. “They also know that the cheapest possible way to make sure that everyone gets the health care that they need is Medicare for All.”

Warren’s aides have long suggested she was studying ways to pay for the health care plan originally backed by Vermont Sen. Bernie Sanders, one of her leading rivals for the 2020 Democratic presidential nomination. In recent days, Warren has faced criticism from lower-profile candidates in the race — especially South Bend, Indiana, Mayor Pete Buttigieg and Minnesota Sen. Amy Klobuchar — for her failure to explain how she would pay for the ambitious plan, which would replace private health insurance with generous, universal coverage paid for by the federal government.

“I plan over the next few weeks to put out a plan that talks, specifically, about the cost of ‘Medicare for All’ and how we pay for it,” Warren said at the end of a town hall here at Simpson College. “I will not sign a bill into law that does not reduce the cost of health care for middle-class families.”

INDIANOLA, Iowa — Massachusetts Sen. Elizabeth Warren said Sunday she will roll out a plan to pay for an expansive single-payer health care system in the coming weeks, promising the plan would decrease overall costs for the middle class.

Warren’s statement came after her standard 40-minute stump speech and three questions from attendees, none of whom asked about Medicare for All. The addition appeared to be an attempt to short-circuit recent criticisms of her health care plan.

Warren has previously promised, most recently at the Oct. 15 debate, that no middle-class family would see an increase in overall health care costs. And her aides have said since at least September that she was evaluating ways to pay for Medicare for All. She does not plan to significantly alter the details of the legislation she’s co-sponsored with Sanders in the way Sen. Kamala Harris (D-Calif.) did with her own health care proposal over the summer. Warren said she had been working on the problem of how to pay for the legislation for “months and months.”

“It’s just a little more work until it’s finished,” she said.

For a campaign that has long prided itself on detailed policy proposals, releasing a plan to pay for Medicare for All — which is sure to generate intense scrutiny from the media and her rivals for the nomination — is a high-risk but likely necessary move. Whether or not a plan for Medicare for All would lower costs for the middle class would rely heavily on complicated details, including how progressive the tax system supporting the plan is and how aggressively the government is able to control the cost of health care.

Estimates of how much the plan would cost vary wildly, as do estimates of how much switching to a single-payer system would increase or decrease overall health care costs.

Buttigieg, in particular, has aggressively questioned how Warren would pay for the plan, and said she is being dishonest by not saying whether or not taxes would go up for middle-class families. Sanders has said taxes would likely go up, while overall costs would drop. But Warren has resisted the question, arguing that admitting taxes would rise is equal to accepting a dishonest Republican framing of the issue. Warren has also attacked Buttigieg’s plan for failing to cover every American, dubbing it “Medicare for all who can afford it.”

“Your signature, Senator, is to have a plan for everything. Except this,” Buttigieg said at the debate. “No plan has been laid out to explain how a multi-trillion-dollar hole in this Medicare for All plan that Senator Warren is putting forward.”

Soon, Buttigieg will get his answer.