This post has been updated.

In Durham County, N.C., election officials were dismayed to discover when the polls opened at 6:30 a.m. Tuesday that some of the laptop computers that precincts were using to verify voter registration had malfunctioned, forcing them to cross-check by old-fashioned paper poll registries.

“We’re going to be using paper all day … the old-fashioned way,” said Kate Cosner, the County Board of Elections interim director. “The state Board of Elections is aware of the problem, and we’re both in agreement that this is the best way to go.”

The problem will likely cause longer lines throughout the day, Cosner said. She added that she didn’t know the cause of the malfunction. “We’re trying to get [precincts]  more poll books just as fast as we can,” she said.

The county traditionally leans heavily to the Democrats — Barack Obama won more than 75 percent of the county’s vote in both 2008 and 2012. North Carolina is considered a key swing state in this year’s presidential election.

Officials initially thought laptops countywide were affected. But Board of Elections spokeswoman Briana Kahn said the board received reports from “five or six” precincts where the laptops were malfunctioning and decided to switch to paper poll books throughout the county “as a precaution.” Individual precincts did have the paper registries on hand Tuesday morning as an emergency backup, Kahn said.

The county has used the computerized check-in system since October 2015, Kahn said. “It’s not an individual laptop issue,” she said. The county uses VR Systems of Tallahassee as its vendor for the check-in laptops but not for its voting machines.