"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," the opening statement introducing the pledge read.
Mrs Bachmann and Rick Santorum, another Republican candidate, signed the pledge, which condemned gay marriage, abortion, infidelity and pornography.
There was a wave of criticism from the Left and bloggers. "If you took a cracked pot and you cracked that cracked pot, you'd be approaching the level of cracked pottery we are talking about here," said Rachel Maddow, a liberal host on MSNBC.
"Given that families were broken up regularly for sales during slavery and that rape by masters was pretty common, this could not be more offensive," wrote Cheryl Contee on her blog Jack and Jill Politics, mainly about black issues.