A voting system used in 34 states contains a critical programming error that can cause votes to be dropped while being electronically transferred from memory cards to a central tallying point, the manufacturer acknowledges.

The problem was identified after complaints from Ohio elections officials following the March primary there, but the logic error that is the root of the problem has been part of the software for 10 years, said Chris Riggall, a spokesman for Premier Election Solutions, formerly known as Diebold.

The flawed software is on both touch screen and optical scan voting machines made by Premier and the problem with vote counts is most likely to affect larger jurisdictions that feed many memory cards to a central counting database rapidly.

Riggall said he was "confident" that elections officials through the years would have realized votes had been dropped when they crosschecked their tallies to certify final elections results and would have reloaded cards so as not to lose votes. Ohio Secretary of State Jennifer Brunner has said no Ohio votes were lost because the nine Ohio counties that found the problem caught it before primary results were finalized.