Rick Perry's tax proposal would undermine traditional marriage and favor gay families, social conservative Phyllis Schlafly claims.

The 87-year-old Schlafly is the founder of the Eagle Forum, a group formed in opposition to the proposed Equal Rights Amendment. She is also the author of numerous books.

In an op-ed titled Rick Perry's Marriage Problems published at Creators.com, Schlafly hits at Perry's tax reform plan and suggests he favors gay marriage.

“Does Rick Perry want to undermine traditional marriage?” Schlafly writes. “This question leaps out from his new 20 percent flat-tax plan, which would eliminate all tax advantages for married couples where one spouse is the primary breadwinner.”

“If an income tax were truly 'flat,' filing status wouldn't matter because a wife is taxed at the same rate as her husband. But Perry's so-called flat tax isn't anywhere near flat, so it matters greatly that he offers the same standard allowances for alternative lifestyles as for married couples.”

Such a tax system would mean “rewarding bad behavior.”

Perry's tax proposal, Schlafly argues, should be viewed with skepticism because he's “been on probation with pro-family voters since July when he told an elite group of big-money donors in Aspen that he was 'fine' with gay marriage in New York because 'that's their business.'”

(Related: Rick Perry lauds effort to repeal gay marriage in New Hampshire.)