The state Democratic Party filed a federal lawsuit accusing Florida's secretary of state of violating federal law when she told elections supervisors to reject incomplete voter registration forms.
The party asked a judge to order Glenda Hood, a Republican, to reverse her instructions to the state's 67 counties.
Hood's office told counties they should disqualify voters who failed to check a box confirming they are U.S. citizens, even if they signed an oath on the same form swearing they are. She and other state officials maintain that state and federal laws require the box to be checked.
"The Secretary of State's Office says they want to err on the side of the voter, yet they want to disenfranchise people," party Chairman Scott Maddox said.
Some counties have said they had no plans to follow Hood's policy as they process the flood of forms coming in ahead of Monday's registration deadline.
This voter registration issue is sensitive because after George W. Bush took office in 2001, federal civil rights monitors concluded that the ballots of black Florida voters were disproportionately tossed out in the 2000 election, which was plagued by faulty machinery and ballot problems in the state.
The Democrats' lawsuit marks the fourth time since August that the party has taken Hood and her office to court. The Democrats successfully challenged plans by the state to reopen qualifying for a state Senate seat in southwestern Florida but were thwarted in their effort to keep Ralph Nader off the presidential ballot.