Election candidates rarely denounce their own supporters, and it is unlikely that U.S. Sen. Mary Landrieu will ever heed the advice of Congressman Bill Cassidy anyway.

Because his prime objective is to run her out of office before the year is over, she isn’t about to thank him for showing her the error of her ways. His invitation to join him in opposition to the teachers’ union’s charter school lawsuit was not the kind that comes with an RSVP.

Posturing is part of the campaign game — in fact, it’s pretty much all it consists of — and Cassidy’s ploy is a standard one. It would be insulting to suggest he expects to be taken seriously.

A Republican candidate is wise to proclaim an enthusiasm for charter schools regardless, but Cassidy’s is no doubt genuine. He and his wife have a dyslexic daughter and played a major role in establishing a charter school for children with the same condition. They say the lawsuit threatens the school’s very existence. Cassidy’s wife calls on Landrieu not only to condemn the lawsuit but to repudiate the union’s endorsement.

A display of ingratitude to a Democratic power base would not be widely regarded as tactically sound on Landrieu’s part, especially as this election figures to be mighty close. Republicans, needing six more seats to gain control of the Senate, seem increasingly confident that Landrieu’s is ripe for the plucking.

She, though not about to thank Cassidy for his suggestion, won’t knock charters either. She issued a statement pointing out that she had secured funding for them. “I stand by my longtime position that parents and families in Louisiana should have high-quality options when it comes to public education, whether that’s a traditional public school or a public charter school,” she said.

The teachers’ union lawsuit is not going to destroy charters anyway, just as its earlier successful challenge to school vouchers made no difference in the long run either. The courts agreed with the union that it was unconstitutional for the state to take money from what is known as the Minimum Foundation Program to pay tuition in the private sector for students transferring from lousy public schools. The money that was going for vouchers, the courts ruled, was constitutionally earmarked for local education authorities.

The success emboldened the union to assert that it is similarly unconstitutional for MFP money to be diverted to private companies that run charter schools, which, while technically public, have considerable autonomy. Logic says the union will win this one, too, but taxpayers will still be stuck with the tab for Gov. Bobby Jindal, and legislators will do what they did with vouchers and juggle the pot. Out will come enough unencumbered moolah to keep the charters in business.

The knock against charters and vouchers is largely the same, and both have required taxpayers to subsidize schools that may have abysmal academic standards and curricula that include such pish-tosh as creationism. Their proponents have nevertheless met with some success in portraying New Orleans as the center of imaginative reforms that could change the face of education nationwide.

The evidence hardly supports those claims. The newsmagazine The Nation has just produced a special section branding charter schools a failure, while Charles Hatfield, whose nonprofit analyzes test scores in New Orleans, does not see any reason to celebrate them either.

Still, charter schools and vouchers do offer parents a choice in where to educate their kids and may therefore encourage a spirit or competition that can only improve matters. Presumably there wouldn’t have been charter schools or vouchers in the first place if parents were satisfied with the traditional model. Such was the level of incompetence and corruption in New Orleans that it seemed any change would be for the better, and taxpayers were largely silent as millions of their dollars were siphoned off to private interests.

That hardly suggested that teachers’ unions were held in high esteem, and so it evidently remains, especially on the right. Cassidy has much riding on the anti-union vote and would never call on Landrieu to agree if he thought there was any chance she would.

James Gill can be reached at jgill@theadvocate.com.