This has been coming for a while. After the bipartisan launch of No Child Left Behind and the desire to advance bipartisan support during the Obama administration (and into the presumed Clinton administration thereafter), a kind of deal was worked out between the right and the left, and school choice was presented as a hybrid that could appeal to both right-tilted free marketeers and left-leaning social justice advocates (profiteers, as always, are both politically agnostic and financially opportunistic).
Strike up a debate about school choice and you were as likely to hear about the power of competition and the free market as you were how school choice would finally bring equity and uplift to children trapped in an inequitable system.
But then the truce began to crumble. Trump and Betsy DeVos didn't help--suddenly certain policies were toxic for lefties. But the fault lines were noted even earlier. In 2016, Robert Pondiscio (AEI) drew some reformy ire by saying out loud that the left and right were not getting along any more. A year and a half later, Kate Walsh (NCTQ) was wondering if the movement had lost its way, citing a new orthodoxy that required reformsters to Be Performatively Sad about certain past failures.
Many observers have followed this dissolving partnership (Jennifer Berkshire has covered it exceptionally well-- try here and here) looking at the causes. Part of the issue has been that Democrats were always the junior partners; school choice has been near and dear to conservative hearts for generations, while Democrats were brought into the fold more recently. Often they were simply Democrats of convenience, as typified by Democrats for Education Reform (DFER), a group whose creation hedge funder Whitney Tilson described thus:“The real problem, politically, was not the Republican party, it was the Democratic party. So it dawned on us, over the course of six months or a year, that it had to be an inside job. The main obstacle to education reform was moving the Democratic party, and it had to be Democrats who did it, it had to be an inside job... In fact, our natural allies, in many cases, are Republicans on this crusade, but the problem is not Republicans. We don’t need to convert the Republican party to our point of view…”