Voter fraud and voter-registration fraud are, of course, different.

While many states have voter registration records riddled with names of dead people, out-of-date addresses and other erroneous information, there is little evidence that such errors lead to fraudulent votes, many experts note.

A report by the public-integrity section of the Justice Department found that from October 2002 to September 2005, the department charged 95 people with “election fraud”; 55 were convicted.

Among those, fewer than 20 people were convicted of casting fraudulent ballots, and only 5 were convicted of registration fraud. Most of the rest were charged with other voting violations, including a scheme meant to help Republicans by blocking the phone lines used by two voting groups that were arranging rides to get voters to the polls.

Even so, the fear of stolen votes remains, as does the fear of missing votes  particularly in light of a decrease, compared with 2006, in voter-registration applications in swing states.

About 43 percent fewer new voters have registered in Wisconsin this year than in 2006, while in Indiana, the decrease has been about 35 percent. Significant drops have also been seen in Ohio (25 percent), North Carolina (28 percent), Florida (27 percent) and Maryland (21 percent), according to state election data collected by the Brennan Center.

Voting experts say several factors explain the trend.

Voter enthusiasm is low now, and fewer groups like the Association of Community Organizations for Reform Now, or Acorn, are engaged in drives to sign people up. Acorn collected about 550,000 voter-registration applications across the country in 2006, mostly from low-income and minority Americans, and 1.3 million in 2008.