"The sleepover issue is fairly egregious," said Lehto. Tampering with one card in one device conceivably could change race results.

The suit also alleges that keys for touch-screen voting machines were released to poll workers -- which is a violation of state and federal law. In addition, the suit cites a recent report that alleges testers discovered a "heretofore unknown switch" in the circuitry of the Diebold TS touch-screen system, the predecessor to the TSx. This allows the machine to boot from an external source, which would circumvent the software and safeguards inside completely.

The suit accuses Haas of suppressing or not collecting relevant materials, such as audit logs and electronic programs and ballots, for potential review after the election.

Haas declined to comment in detail about the suit, citing pending litigation, but he did defend the sleepover practice as being something commonly done in California and other states.

"Supervising poll workers take all supplies home following a training class so they are prepared. They are directed to keep it [the machine] secure wherever they are responsible for it," he said.