The Obama Administration has gone to the mat to try to prevent states from verifying the citizenship of their registered voters.
Registering and voting by non-citizens is a felony under federal law, and Florida has already found aliens on its voter rolls, some of whom voted in prior elections. Almost as soon as Florida announced that the Department of Homeland Security (DHS) would allow the state access to DHS databases, critics started complaining about the supposed inaccuracy of the DHS information (including an election law professor I debated on Los Angeles public radio).
Florida had been trying to get this access for the past year (as has Colorado). It had to sue DHS last month to force the agency to finally comply with federal law, which mandates that the government provide such citizenship verification information to the states.