Errors by Census Bureau employees may have resulted in 200 people with criminal records being hired to conduct door-to-door canvassing.

The Census Bureau typically takes fingerprints and performs background checks on workers hired to interact with the public. But a report by the Government Accountability Office (GAO) found that tens of thousands of workers were improperly fingerprinted by bureau employees.

The GAO fears that the name-checks performed on those employees were not sufficient without fingerprints.

"It is possible that more than 200 people with unclassifiable prints had disqualifying criminal records but still worked and had contact with the public during address canvassing," Robert Goldenkoff of the GAO said in a report to a Senate subcommittee on Wednesday.

Goldenkoff cited the "adequacy of the bureau's training" as a reason for the improper fingerprints.

He said the bureau "will refine instruction manuals and provide remediation training on proper procedures" to prevent the problem from recurring.