But it’s an issue that policymakers can no longer afford to ignore. The cost of child care has increased nearly exponentially in recent decades, far outpacing inflation. Now it consumes more of the average family’s budget than health care, transportation or food, and in most places it rivals housing, too. Full-time center care often costs more than tuition and fees for public college. That money still doesn’t buy quality, though. A 2006 survey found that fewer than 10 percent of American day care centers provided high-quality care. And that’s for the families lucky enough to get their child a spot: More than half of Americans live in a neighborhood without enough child care seats for all the children who need them.

Even the Democratic presidential hopefuls who didn’t release plans as detailed and bold as Ms. Warren’s or Mr. Sanders’s talked about child care. Amy Klobuchar sponsored the Child Care for Working Families Act, a Democratic proposal in Congress with similar aims of universal coverage. Mike Bloomberg’s early-education plan supported higher-quality and lower-cost child care and universal preschool. Even President Trump has talked about child care, proposing on the campaign trail to increase tax deductions to cover the cost and calling for a one-time $1 billion investment in his White House budget.

This is a vast, complicated crisis that is dampening our entire economy. It makes sense for presidential hopefuls to put forward ideas that are bold enough to match the stakes.

But so far, although Mr. Biden has supported universal preschool in the past, he has been more or less silent on what parents of younger children should do. And while today he supports an increased child tax credit that can help families cover the cost, he wrote an op-ed article in 1981 arguing that the credit subsidizes the “deterioration of the family” and “encourages a couple” to “evade full responsibility for their children” by helping them put those children in day care. The article argued against any universal government child care assistance because it would go to well-to-do families, but it also repeated language from Republicans who fearmongered about child care.

The best way for Mr. Biden to disavow any antiquated positions and to assure voters that he is in tune with their most pressing needs would be to release his own universal child care plan. He doesn’t have to reinvent the wheel; he can simply look back at our own history and take inspiration from what we would have had if things had gone slightly differently.

Better late than never.