Of course there are no significant details yet, but here are a few points.
1. The evidence that this can be done effectively in a scalable manner is basically zero. Aren’t massive policies (possibly universal?) supposed to be based on evidence? (How about running a large-scale RCT first, a’la the Rand health insurance experiment? And by the way, here is a quick look at the evidence we have on pre-school, and here, not nearly skeptical enough in my view. And think in terms of lasting results, not getting kids to read nine months earlier, etc. You can find evidence for persistent math gains in Tulsa, OK, but no CBA.)
2. That doesn’t mean we should do nothing.
3. Let’s say we have “the political will” to do something effective (debatable, of course). Is adding on another layer of education, and building that up more or less from scratch in many cases, better than fixing the often quite broken systems we have now? I know well all the claims about “needing to get kids early,” but is current kindergarten so late in life? Why not have much better kindergartens and first and second grade experiences in the ailing school districts? Or is the claim that by kindergarten “it is too late,” yet a well-executed government early education could fix the relevant problems if applied at ages three to four? Would such a claim mean that we are currently writing off many millions of American children, as it stands now?
4. This is what federalism is for. Let’s have an experiment emanating from the state and/or local level.
5. What should we infer from the fact that no such truly broad-based state-level experiment has happened yet? (Georgia and Oklahoma have come closest.) That the states are lacking in vision, relative to the Presidency? Or that a workable version of the idea is hard to come up with, execute, and sell to voters?
6. In Finland government education doesn’t really touch the kids until they are six years old. Don’t they have a very good system? Some call it the world’s best. Maybe the early years are very important, but perhaps pre-schooling is not the key missing piece of the puzzle. (NB: See the comments for dissenting views on Finland.)