No family would have to spend more than 7 percent of its household income on child care, no matter the number of kids. Families with incomes below twice the poverty line, which is roughly $50,000 a year for a family of four, would pay nothing.

Only providers that meet federal safety, staffing and curriculum standards could qualify for the funding.

Officials with Warren’s 2020 presidential campaign declined to comment on the proposal and the sources familiar with the plan cautioned that some details were still in flux as of last week.

But, the sources said, the campaign has an internal analysis that shows the initiative will likely require approximately $700 billion in new federal spending over 10 years. That is a net figure, taking into account higher economic benefits of early childhood investments, such as making it easier for new parents to return to work.