Another way to solve the problem, he said, is to drop touchscreens in favor of other vote input systems. One e-voting machine vendor, Hart InterCivic Inc., uses a wheel on their machines that voters rotate to make their candidate choices, and a separate button to confirm the choice, he said. Another option would be to build systems that incorporate actual buttons for voters to use to make their choices, he said.

Michelle Shafer, a spokeswoman at e-voting machine vendor Sequoia Voting Systems, said the perceived problem of vote flipping is definitely human error or procedural error and not a problem with the systems themselves.

"Sometimes the machines need to be calibrated or recalibrated," Shafer said. "Machines in and of themselves do not flip votes."

Since the hardware displays voters' choices before their electronic ballots are cast, voters can spot any inadvertent errors and should immediately contact a poll worker if they believe an incorrect selection has been made, she said.

What appears to be a flipped vote, she said, is more likely a situation where a voter has too many fingers touching the machine, has long fingernails or is leaning on the equipment. "There's many, many reasons that this type of thing occurs [accidentally]," she said.