Who'd have thought that one of the most hotly contested Cabinet nominees would be for the education department?

The teacher unions are pulling out the stops to prevent school choice advocate Betsy DeVos from becoming secretary of education. And they have peeled off some natural allies of Devos, as an editorial in this morning's Wall Street Journal notes.

Eli Broad, one of the nation's foremost charter school funders, has sent a letter to Congress that opposes DeVos and that "parrots the union talking points about the grave threat Mrs. DeVos poses to public schools." Broad expressed concern for what he called DeVos' "support for unregulated charter schools and vouchers.”

The Journal suggests that Broad should know better:

[S]urely Mr. Broad knows that charters have to comply with most of the same rules as traditional public schools including the federal Individuals with Disabilities Education Act, anti-discrimination laws and state standardized testing. Charters are authorized by government entities, and chronically low-performing schools in most states can be forced to close.

Charters have more freedom to innovate because they aren’t hemmed in by union collective-bargaining agreements. They can hire and fire teachers at will, base pay on performance and require longer school days. Mr. Broad, this is what unions mean when they accuse Mrs. DeVos of supporting “unregulated” schools.

Voucher and scholarship programs are also tightly regulated, and sometimes more than public schools. In most states, scholarship and voucher recipients must take standardized tests. Louisiana requires a curriculum at least as rigorous as public schools and restricts participation for low-performing private schools. Private schools must submit to independent financial audits.

The Massachusetts Charter Public School Association wrote a letter to Senator Elizabeth Warren that was strikingly similar to Broad's letter to Congress.

The group adds that “the same researchers from Stanford that declared Massachusetts charter public schools an unqualified success, had mixed reviews for Michigan’s charters.” In fact, Stanford’s Center for Research on Education Outcomes found that Michigan charter students on average gained an additional two months of learning every year over traditional school counterparts and those in Detroit gained three months.

Vouchers and charters can co-exist. Louisiana and Washington both have robust voucher programs. Yet more than 90% of public school students in New Orleans and nearly half in D.C. attend charters. While Ohio and Indiana boast fast-growing voucher programs, charters educate 30% of public-school students in Cleveland and Indianapolis.

If anything, vouchers make it safer for charter schools because they deflect union attacks. Charters are most vulnerable in states that don’t have private-school choice programs—such as New York, California and Massachusetts. As soon as the voucher threat is defeated in a state, the unions attack charters with regulations, caps and attempts to unionize.

The Journal suggests that school choice advocates "hope to buy political protection by throwing Mrs. DeVos to the wolves." Broad in particuar should know how futile this endeavor will be:

In 2015 the Los Angeles Times reported that Mr. Broad and other charter supporters aimed to raise a half billion dollars to enroll half of Los Angeles’s public school students in charters (up from about 16%). Unions then accused the billionaire of trying to destroy public schools. Sound familiar? When charter advocates extended an olive branch to the unions by establishing a grant for high-quality public schools in low-income areas, local teachers union President Alex Caputo-Pearl called it “an insulting billionaire publicity stunt.”

DeVos is not an enemy of public education, but she "understands the key to improving schools is to break the union’s government monopoly" in the public schools. If DeVos is defeated it will be a victory for the unions and a setback for school choice, the future of which seemed bright with the nomination of DeVos.

Republican Senators Lisa Murkowski of Alaska and Susan Collins of Maine, both of whom have received significant donations from the teachers union, have announced that they will vote against DeVos. The unions need only one more Republican to set back the cause of school choice.