John Wilson of the National Education Association said TFA brings "the least-prepared and the least-experienced teachers" into low-income schools.
"TFA has done a marvelous job of marketing their program. But what they're doing to poor children is malpractice," Wilson told USA Today.
TFA teachers are "educational mercenaries," Detroit teachers union President Keith Johnson said, adding they "ride in on their white horses and for two years share the virtue of their knowledge as a pit stop on their way to becoming corporate executives."
TFA is a program designed to lure top college students into teaching in urban and rural settings for a two-year commitment. Only 29 percent stay in the classroom, a 2008 survey revealed, but only 4 percent go into business.
TFA spokeswoman Kerci Marcello Stroud said TFA corps members are not displacing experienced teachers. "In every region where we send teachers, we're just one source," she said.
Peter Gorman, superintendent of the Charlotte-Mecklenburg, N.C., school district, said in March he was laying off many teachers but sparing 100 TFAers because the district "made a commitment to this program" and TFA teachers "are placed at schools with high populations of underprivileged students where the placement of personnel has proven to be difficult."