For instance, when testing the program the TSA enrolled and issued TWIC cards to only about 1,700 workers -- far short of its original plan to issue cards to 75,000 workers during the test. According to the GAO, the TSA is using the information gleaned from that limited testing to improve its card enrollment and issuance processes for the entire maritime sector. It also plans to use an easier and faster form of fingerprint scanning based on results gleaned from its program test.

"While these actions should address the problems that occurred during testing, during implementation [the] TSA faces the challenge of enrolling and issuing TWIC cards to 750,000 workers at 3,500 maritime facilities and 10,800 vessels -- a significantly larger population of workers," the GAO noted.

The TSA also has gathered only limited information related to the "operational effectiveness" of biometric card readers in "harsh" maritime conditions, the GAO report said. That's because only a few of the facilities involved in the TWIC testing program used biometric devices. In addition, the testing facilities did not have the technology to link back with TSA's central TWIC database to get current information on workers, the report noted.

Pressure to begin TWIC testing also led TSA officials to award a contract "before they had sufficient time to plan for and identify all of the requirements necessary to test the TWIC program," the GAO report said. As a result, the testing project was poorly supervised and failed to check all of the components of the TWIC program.

As a result of those concerns, the TSA needs to first "develop and test solutions" for enrolling and issuing cards to a large number of individuals before implementing the overall project, the GAO said. It also called on the TSA to "strengthen contract planning and oversight practices before awarding the contract to implement the TWIC program."