This is as close as I can find to a transcript. There’s video at the link:
Speaking at an Iowans For Tax Relief event, Bachmann (R-MN) also noted how slavery was a “scourge” on American history, but added that “we also know that the very founders that wrote those documents worked tirelessly until slavery was no more in the United States.”
“And,” she continued, “I think it is high time that we recognize the contribution of our forbearers who worked tirelessly — men like John Quincy Adams, who would not rest until slavery was extinguished in the country.”