Commission officials said that they were evaluating the overall diligence of the laboratory and that they did not try to determine whether its weaknesses had contributed to problems with specific machines.

Computer scientists have shown that some electronic machines now in use are vulnerable to hacking. Some scientists caution that even a simple software error could affect thousands of votes.

In various places, elections have been complicated by machines that did not start, flipped votes from one candidate to another or had trouble tallying the votes.

Until recently, the laboratories that test voting software and hardware have operated without federal scrutiny. Even though Washington and the states have spent billions to install the new technologies, the machine manufacturers have always paid for the tests that assess how well they work, and little has been disclosed about any flaws that were discovered.

As soon as federal officials began a new oversight program in July, they detected the problems with Ciber. The commission held up its application for interim accreditation, thus barring Ciber from approving new voting systems in most states.

Ciber, a large information technology company, also has a $3 million contract to help New York test proposed systems from six manufacturers. Nystec, a consulting firm in Rome, N.Y., that the state hired, filed a report in late September criticizing Ciber for creating a plan to test the software security that “did not specify any test methods or procedures for the majority of the requirements.” The report said the plan did not detail how Ciber would look for bugs in the computer code or check hacking defenses.

A spokeswoman for Ciber, Diane C. Stoner, said that the company believed that it had addressed all the problems and that it expected to receive its initial federal accreditation this month. Federal officials said they were evaluating the changes the company had made.