The survey was released last month.
The body's president and 15 representatives signed onto a letter to UMD officials.
The average undergraduate GPA increased by 0.09 in the spring from the previous two semesters.
Since the grading policy announcement, opposition has been fierce.
Some TAs say they've seen a spike in attendance at their office hours.
The university returned to its standard grading policy this semester, despite many students remaining virtual.
The portal for opting into letter grades initially closed on May 12.
The university should use the transition to online classes as an opportunity to refine its approach to blended learning.