Voter ID laws: Democrats vs Republicans

Seeing this story on the effect of new voter ID laws in Florida appear in several blogs, I chased it down to ensure it really does seem genuine; here is the original article in the Florida Times-Union:

On July 1, 2011, a sweeping election law overhaul passed by the Legislature put new restrictions on groups that hold voter registration drives. Among the changes, groups were required to file new voter registration applications with election officials within 48 hours, instead of the old 10 days, or face a penalty.
Groups said the new rules made it impossible to comply. As a result, many got out of the registration game until a federal judge ruled in their favor at the end of May, 11 months later.
"It has without a doubt hurt registration numbers," said Deirdre Macnab, president of the nonpartisan League of Women Voters of Florida. "It really gummed up the works and made it harder for Floridians to get registered."

So the effect seems to be less clear-cut than the headline figures. It's obvious that the Democratic approach to registration is hit much harder by this change than the Republican approach, but I'm intrigued as to why. What was it about the change to a 2-day registration process that made Democratic registration groups so indignant, and effectively put the kibosh on their activity, but still allowed Republican groups to conform to the change and increase their registration numbers from previous years? What is it about the Democratic unregistered voters that makes them so time-consuming to register?

What will be interesting is to see the figures post-June when the registration time has reverted to 10 days. Can the Democrats pick up the slack, or will they continue to have problems with the new voter ID law? Time will tell. What these stats don't show, in themselves, is the effect that requiring voter ID has on new voters.