Sharon Lettman, vice president for external affairs for the Washington-based People for the American Way Foundation, said problems are already showing up as voters cast ballots in early-voting programs. Some problems are related to machines that are incorrectly switching votes, giving them to the wrong candidates, she said.

Her advice for voters having problems is simple. "Most importantly, don't take no for an answer," Lettman said.

Ask for help immediately before finalizing your votes if there is a problem, or call the hot line to report problems or get assistance, she advised.