Indianola, Iowa (CNN) Massachusetts Sen. Elizabeth Warren committed for the first time on Sunday to putting out a plan detailing how "Medicare for All" would be funded, after facing criticism and being pressed on how she would pay for the national health insurance plan without raising taxes on the middle class.

"We need to talk about the cost, and I plan, over the next few weeks, to put out a plan that talks about specifically the cost of 'Medicare for All' and specifically how we pay for it," Warren said at a town hall in Indianola, Iowa, on Sunday. She told the crowd gathered that the plan "is something I've been working for months and months, and it's got just a little more work until it's finished, but I want to bring this out."

"I think there have been many estimates about what the cost will be, and many different payment streams, and I've been working on how to give the exact details to make that work," the Democrat told reporters on Sunday, adding later that she's "ready to put out a plan soon on exactly what the costs will be, and how to pay for it."

Warren's campaign said last week it was studying a range of options for paying for Medicare for All, leaving open the possibility that the senator may ultimately diverge from Vermont Sen. Bernie Sanders on how to pay for his sweeping health care plan -- which Warren has endorsed. Warren has not outlined her own health care plan , and instead is running on Sanders' single-payer legislation that she first signed on to in 2017.

Warren spoke for more than an hour at the event in Indianola before making the announcement. The campaign hoped she would simply mention her upcoming plan when asked about health care, but Warren was not asked the question at the town hall so she delivered this pre-planned message at the end of the event.

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