I think I got some of my figures wrong in the previous post on Greg Palast. Florida is one of six (seven?) states that bar convicted felons from voting. Since this group of potential voters is overwhelmingly Democratic, disenfranchising them can have a significant effect on elections.

From CNN.com - CNN asks Florida court for ineligible voters list - May 28, 2004:

"In the 2000 election, state officials purged voter rolls of the names of more than 173,000 people identified as felons or otherwise ineligible to vote, but civil rights activists as well as some Florida county elections supervisors have charged that those lists contained numerous errors, and that thousands of eligible voters were prevented from casting ballots in the election.

After the Supreme Court closed the door to recounts, President Bush edged then-Vice President Al Gore in Florida by a margin of 537 votes, enough to win the state and, with it, the White House.

'Florida's 2000 felon purge program resulted in over 50,000 legal voters being disenfranchised,' said Leon County elections supervisor Ion Sancho in a written statement. 'When asked for assurances that the [2004 felon list] was 90 percent accurate -- the minimum level local supervisors of elections requested for such a list -- we were told that it was better than the 2000 list, with no data to support its accuracy.'"