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.

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.

Warrens 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.

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.