Rick Perry has become the third Republican presidential candidate to sign a marriage vow promoted by a Christian activist group in Iowa.

The Family Leader, a powerful force among Iowa's socially conservative voters, introduced the vow in July, and candidates Michele Bachmann and Rick Santorum signed it right away. The pledge quickly came under fire, though, for a passage that implied that black children were better off under slavery.

Slavery Clause Dropped

The passage -- which read, Slavery had a disastrous impact on African-American families, yet sadly a child born into slavery in 1860 was more likely to be raised by his mother and father in a two-parent household than was an African-American baby born after the election of the USA's first African-American president -- was quickly deleted, but the appeal of the pledge seemed to dim, with no candidates other than Bachmann and Santorum signing it for more than four months.

Perry's signature has revived the pledge, putting it back in the spotlight, and Perry hopes it will do the same for his campaign. The Texas governor is polling in the single digits after a series of gaffes, including an embarrassing brain freeze at a recent Republican debate in which he could only remember two of the three federal agencies he wanted to eliminate.

Bob Vander Plaats, the president of The Family Leader, has said that signing the pledge is a prerequisite for any candidate hoping to get the group's endorsement -- and at this point, Perry cannot afford to forfeit any prominent endorsement, much less that of a group whose support could be the key to the Iowa caucuses.

Appealing to Same Voters?

He is trying some Hail Mary passes late in the game, Doug Gross, a Republican strategist who advised Mitt Romney in 2008, told the Des Moines Register. This one probably won't work since he is appealing to the same voters as are a number of the other candidates, when he should be focusing on a core group who don't want Romney and have nowhere else to go.

Signers of the pledge promise to oppose any redefinition of the institution of marriage -- faithful monogamy between one man and one woman -- through statutory-, bureaucratic- or court-imposed recognition of intimate unions which are bigamous, polygamous, polyandrous, same-sex, etc., and to support a federal constitutional amendment that would define marriage as between a man and a woman.

They also pledge, among other things, to be faithful to their spouse, to appoint none but faithful constitutionalists to federal courts, to oppose Sharia law, to recognize that robust childbearing and reproduction is beneficial to U.S. demographic, economic, strategic and actuarial health and security, and to promote policies that will protect women and the innocent fruit of conjugal intimacy -- our next generation of American children -- from human trafficking, sexual slavery, seduction into promiscuity and all forms of pornography and prostitution, infanticide, abortion and other types of coercion or stolen innocence.