Universal child care is becoming a central pillar of the liberal agenda — one that, if it is ever realized, could take its place alongside some of the great progressive reforms of the 20th Century, and possibly the Affordable Care Act, as a defining achievement of the Democratic Party.

I’m told that Senate Democrats in coming days will roll out a new universal pre-kindergarten proposal that would be funded by the closing of corporate tax breaks. If it gets a vote — and Dem leaders plan to push hard for one — it will put members of both parties on record as to whether they support national action to dramatically expand the availability of child care to poor and working families.

The proposal — to be introduced this week by Senator Bob Casey of Pennsylvania — is called the Strong Start for America’s Children Amendment, and Casey plans to introduce it as an amendment to a measure reauthorizing and overhauling No Child Left Behind, which will be debated in the Senate starting tomorrow.

The new universal pre-K proposal is meant to function as a federal-state partnership. It would provide over $30 billion in federal block-grant funding, over five years, to states that provide high quality, universally available pre-school programs to four-year-olds from families earning less than 200 percent of the Federal Poverty Level, or $48,000 for a family of four. Any state that already has such a program can use the money to expand it to three-year-olds; states could also provide subgrants to local governments that establish pre-K programs that meet predetermined standards.

The program would be funded by the scaling back of “corporate inversions,” in which companies declare that their U.S. operations are owned by a subsidiary abroad, resulting in profits being shifted to places where they are taxed at lower rates. The proposal would reconstitute an earlier Dem proposal that would require companies to be at least 50-percent foreign owned to use the technique, rather than the current requirement that it only be 20-percent foreign owned, lowering the incentive for companies to resort to the practice, which members of both parties have condemned.

“We’re trying to dis-incentivize what most public officials agree is a bad practice — corporate inversions,” Senator Casey tells me. “But we’re also boosting something that officials and corporate leaders say they favor, which is investing in early learning.”

“We’ve had states make substantial progress on early learning over the past 20 to 25 years,” Casey adds. “But on the federal level there really hasn’t been a strategic commitment to it. This will adversely impact wage growth, competitiveness and GDP growth. If we’re going to talk about jobs and wages, it starts with early learning. Studies show a link between learning and earning — if kids learn more now, they’ll earn more later.”

A senior Dem leadership aide tells me that this will be a “key amendment” for Democratic leaders, adding: “we intend to push hard to get a vote.” This could conceivably be helped, this aide notes, by the fact that Republicans, too, want to vote on amendments.

Now, obviously the proposal may not end up getting a vote, and even if it does, it almost certainly won’t pass the GOP-controlled Senate. “It’s an uphill climb,” Casey concedes. “For some reason there’s a gap between what CEOs of large corporations tell us they believe is good for the workforce and the economy — investments in early learning — and how Republicans vote. Obviously we have work to do with Republicans, and I hope business leaders will continue to make the case to them.”

But it would nonetheless be a mistake to dismiss this as merely a “message vote” or a political stunt. That’s because universal child care is fast becoming a top priority of progressives and Democrats. It is a major policy idea in two of the leading progressive policy blueprints — the Center for American Progress’s “Inclusive Prosperity” agenda and the Roosevelt Institute’s call for a deep structural overhaul of the rules under-girding the American economy. Both see expanded child care as crucial to removing added barriers to women participating in the workforce. Obama has pushed it; Hillary Clinton will likely make it key to her presidential run.

As Jonathan Chait detailed in a good piece, Dems will continue to push for quality universal child care as the “next major goal of American liberalism.” It brings together several elements of current liberal thought: The idea that social changes resulting in more women entering the workforce have left working families with limited child care options, with disastrous results; and the notion that improving early education pays economic dividends later. Chait concludes:

In addition to its emerging status as party doctrine, early childhood education solves several of Hillary Clinton’s messaging problems at once. Affordable child care as a social issue appeals to the working poor all the way through to the upper middle class. It lends policy heft to her status as potentially the first female president in American history. And it would undergird a forward-looking economic program, simultaneously attacking the problem of stagnant opportunity for working parents and their children.

It took 65 years from the time Harry Truman proposed universal health care for Obama to sign a law actualizing his vision. Universal child care may not happen in the next presidential administration, which will begin with the same implacable Republican Congress that makes Obama’s proposal dead on arrival. But it will eventually happen, and probably in less time.

If so, the Democrats’ push for the current version of the proposal is best seen as one small step in a long, long process.