Two senators active in oversight of the U.S. Postal Service have asked the GAO to review the accuracy of postal performance reports, including “whether there are formal or informal incentives or directives that may potentially cause postal employees to inaccurately collect or record mail performance data,” what controls are in place to detect possible misreporting and what actions USPS takes if it occurs.

Sens. Claire McCaskill, D-Mo., the ranking Democrat on the Senate Homeland Security and Governmental Affairs Committee, and Heidi Heitkamp, D-N.D., said they have received numerous reports of mail delayed to their constituents that call into question the Postal Service’s performance statistics.

“While USPS faced difficulty in the past few years meeting its service standards, it began to see service improvements in 2016,” the senators wrote. “We would ordinarily be heartened to see improvements in service, but these reported improvements often do not align with feedback from our constituents or the reported confusion about how long it takes to send mail from point A to point B,” they wrote.