The GAO's original report, issued Aug. 4, had accused four colleges of encouraging fraudulent practices and all 15 for-profit schools it investigated of engaging in deceptive or questionable practices.
However, U.S. Sen. Mike Enzi, R-Wyo., said in a letter to the GAO Tuesday, a copy of which was received by United Press International, it appeared the investigative agency's Nov. 30 revision contained major revisions among the more than 50 changes made on 12 pages of the original report.
Enzi said the changes "appear to undermine many of the allegations" made by a GAO official, Gregory Kutz, in testimony to a Senate committee, and "suggest that information was intentionally or recklessly omitted and/or misrepresented."
"This is totally unacceptable," Enzi wrote.
The senator said the revisions call into question the "quality and rigor" of the GAO investigation on this issue. Enzi called for the GAO to withdraw its testimony on the matter and provide a detailed explanation of each change it made.
The Washington Post notes the revisions came as the Obama administration and senior Democratic lawmakers are seeking stronger oversight of for-profit higher education.