The story

Eight years after Florida's hanging chads exasperated voters and helped usher in sweeping changes in voting technology, many election observers remain concerned about the accuracy of the electronic voting systems most Americans will use November 4.

Touch-screen machines can occasionally fail or register votes for unintended candidates. Optical-scan systems can have trouble reading paper ballots that are too long or marked with the wrong ink. At least one study suggests that electronic voting machines can be easily hacked.

And some 9 million voters, including many in the battleground states of Ohio and Florida, will use equipment that has changed since March, increasing concerns about errors next Tuesday. Read full article »

CNN correspondent Miles O'Brien and CNN producer Marsha Walton contributed to this report.

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