"Obviously, we made some mistakes," said John Berry, the director of the U.S. Office of Personnel Management (OPM), in a briefing with reporters.

The agency underestimated the capacity of its system, said Berry. "There was no question that we got overwhelmed," he said at the news briefing.

Users complained on OPM's official Facebook page about performance and access issues and search problems shortly after the Oct. 11 relaunch. A major source of frustration involved password resets, which was a necessary part of the transition from Monster, said officials.

The government workers.

Among those taking note of the user frustration was U.S. Sen. John Kerry (D-Mass.), who late last month wrote Federal CIO Steve VanRoekel to urge the administration to "seek a vendor through a competitive bidding process to manage this service." Monster.com is based in Massachusetts.