On Tuesday, a procedural error temporarily left would-be primary voters in 238 precincts in Montgomery County without the ballot cards required to operate the e-voting hardware, according to elections officials. The machines used by the state are from Diebold Elections Systems Inc.

As a result of the snafu, poll workers were left scrambling to provide enough paper-based provisional ballots to voters. And in some cases, even those ran out.

With the nation headed toward what is expected to be a hotly contested congressional election involving seats in a number of states where e-voting systems will be used, any potential for technical or procedural breakdowns gives e-voting critics cause for concern.

The error was as simple as it was disruptive. The voter access cards, which are about the size of a credit card, are given to voters, who insert them into a Diebold AccuVote TSx touch-screen system. The ballot then appears on screen, allowing votes to be cast. However, the access cards needed for Tuesday's primary weren't in the sealed election-supply bags provided to the precinct election judges who oversee voting.

Without the cards, voters had to use provisional paper ballots, although not every polling place provided them. Although every precinct in the county was affected, a few located near the state's election headquarters got cards by 7 a.m., when voting was supposed to start. Other precincts didn't receive them for up to three and a half hours, forcing some voters to be turned away from the polls. Others simply gave up waiting. To compensate for the delayed voting, a judge ordered the polls to stay open an extra hour Tuesday night.