This video from Head Noises betrays the real reason that the Democrats are opposed to school vouchers that would let parents chose which school to send their kids to. They say that it's the teacher's unions, but that's not the real reason. Why would the teacher's unions be afraid of losing money? Shouldn't they instead be excited by the prospect of private schools taking government money, and thereby creating leverage for the government forcing them to unionize? That sort of aggressive taking money by force is much more a typical Democrat strategy than just holding the line.
The real reason that the Democrats want to keep kids in public schools is because they control the schools and it lets them indoctrinate other people's children.
Whenever the Democrats talk about divisiveness (meaning Republican policies), think about that. The Republicans, by and large, are the ones who are willing to compromise, to let people live like they want. It is the Democrats who want to indoctrinate other people's children, who want to teach evolution and sex education to the children of people who don't want that taught their kids, who want the law to legitimize a particular sexual perversion and force people to accept it, who try to pass their cultural changes through the courts when they can't do it by democratic action.
The Democrats have policy decisions that are positively calculated to anger people and cause divisiveness in the country. The Republicans by contrast are willing to look at these areas of intense disagreement and try to find a way for each side to have freedom of conscience.