Hillary Clinton on Tuesday sketched out an agenda for helping families with young children, including an ambitious promise to put high-quality child care within financial reach of all working parents.

Clinton described her vision during an appearance at a social services center in Lexington, Kentucky, that provides subsidized child care to low-income families. It was the second consecutive day in which Clinton, front-runner for the Democratic presidential nomination, focused on work-family issues. And she said the need for government action was clear. "It's time to face up to the reality of what family life is like today and to support families," Clinton said.

The most concrete part of the agenda, first reported by The Huffington Post, is a pair of narrow but potentially important proposals. One would bolster a highly regarded “home visiting” program designed to help low-income children at risk of emotional, intellectual, and physical harm. If Clinton has her way, the program, known as the Maternal, Infant and Early Childhood Home Visiting Initiative, would reach twice as many children as it does today.

The other initiative would seek to boost pay for child-care workers, as a way to improve retention and attract educators with stronger qualifications. Clinton will call this the RAISE initiative, for “Respect And Increased Salaries for Early Childhood Educators,” and it will be based on successful pilot programs now operating in several states.

But the most intriguing part of Tuesday’s proposal was Clinton's call to make sure that no family ever pays more than 10 percent of its income on child-care expenses. To accomplish this, campaign aides said, Clinton would use a combination of subsidized child care and tax credits. The campaign did not provide more information on how these subsidies and credits would work, or how big they would be, saying only that such details would come later this year.

Clinton's goal is audacious, given that many families now spend far more than 10 percent of income on child care. One big challenge is that efforts to improve the quality of child care, like hiring teachers with better credentials, inevitably make it more expensive. A serious effort to make child care better and more affordable simultaneously, as Clinton apparently has in mind, would cost a great deal of money -- money that would have to come from either new taxes or cuts to other programs, given Clinton’s vow to find offsets for any new government spending.

But research has suggested that investments in well-designed early childhood plans can pay off later, by producing adults who are more economically productive and less likely to have trouble in school or with the law. And in the short term, subsidizing high-quality programs for young children can alleviate a major source of financial stress, not just for the poor, but also the middle class. In fact, Clinton aides stressed that Clinton’s guarantee of support would apply to all working families, no matter what their income levels.

Clinton’s announcement is one more signal that early childhood and work-family issues have become high priorities for the Democratic Party and its allies. Sen. Bernie Sanders (I-Vt.), Clinton’s rival for Democratic nomination, has repeatedly labelled the U.S. child care system an “embarrassment,” and has called for the same sorts of substantial investments in early childhood. President Barack Obama has made expansions of government-financed preschool a cornerstone of his recent budget proposals to Congress.

Meanwhile, liberal think tanks have been churning out new early childhood reports, and Heather Boushey, an economist who happens to be an outside adviser to Clinton, recently published a book, "Finding Time," making the case that government should do more to help working families with children.

While supporters of such initiatives have won key victories at the state and local levels, most recently when New York City created a universal pre-kindergarten program, they have failed to win much support in the Republican-led Congress, for a variety of reasons, including the hefty price tag for such programs. The notable exception is the home visiting initiative, which has a history of bipartisan support -- and happens to be relatively cheap.

Republican ambivalence about spending large new sums on early childhood investments is one reason that Clinton’s proposal could set up a stark choice for the general election. The other is the very different profiles of the two likely candidates.

Clinton, who is nearly certain to become the Democratic nominee, has a long history of advocacy on behalf of young children. As a newly minted graduate of Yale Law School, Clinton worked for the Children’s Defense Fund. As first lady in Arkansas, when Bill Clinton was governor, Clinton was credited with starting a program that improved literacy for low-income residents and became a model for similar programs around the country.

Donald Trump, the presumptive Republican nominee, has no such record. Instead, he has a history of saying that he doesn’t like hands-on parenting -- and that he thinks changing diapers is women’s work.

This article has been updated to note Clinton's announcement.