See this New York Times report. A few snippets:

Of nearly 48,000 Florida residents on the felon list, only 61 are Hispanic. By contrast, more than 22,000 are African-American….In a presidential-election battleground state that decided the 2000 race by giving George W. Bush a margin of only 537 votes, the effect could be significant: black voters are overwhelmingly Democratic, while Hispanics in Florida tend to vote Republican….The paucity of Hispanic voters on the felon list was first reported Wednesday, by The Sarasota Herald-Tribune, but officials said then that the problem was not systematic. After The New York Times examined the data, state officials acknowledged that the method for matching lists of felons to those of voters automatically exempted all felons who identified themselves as Hispanic.