TALLAHASSEE, Fla â€"  Federal authorities are demanding that Florida halt its push to remove ineligible voters from the voter rolls.

In a move that comes just months before the state could play a pivotal role in the 2012 presidential election, the U.S. Department of Justice contends that the state is violating federal law in its effort to identify and remove ineligible voters.

The state's effort has already come under fire from local election supervisors who belong to both political parties, as well as Democratic members of Congress and voting rights groups.

Chris Cate, a spokesman for the Florida Department of State, said state officials were still reviewing the letter, but hinted Florida may fight federal authorities.

"Bottom line is we are firmly committed to doing the right thing and preventing ineligible voters from being able to cast a ballot," Cate said.

Florida, at the urging of Republican Gov. Rick Scott, began looking for non-U.S. citizens on its voter rolls last year. An initial search turned up as many as 182,000 registered voters who may not be U.S. citizens.

Earlier this year state officials sent to local election officials a much smaller list of more than 2,600 voters and asked supervisors to start the process to remove them from the rolls.

Supervisors, however, have loudly questioned the accuracy of the list, with one GOP supervisor going on Twitter to show the picture of a U.S. passport of one voter found on the list. Earlier this week two Democratic members of Congress held a press conference with a World War II veteran whose citizenship had been questioned.

Federal officials said that the procedures the state is using to identify non-U.S. citizens has not been reviewed to make sure they are not discriminatory. Florida must get approval for changes in voting procedures because five counties are still covered by the Voting Rights Act of 1965.

T. Christian Herren, chief of the voting section of the civil rights division, also said that removing voters from the rolls less than 90 days before a federal election also appears to violate federal law. Florida's primary election is Aug. 14.

Herren's letter gives Florida until June 6 to tell federal authorities whether they plan to halt the purge.

Voting rights groups who had called on the U.S. Department of Justice to intervene praised the decision.

"We commend the attorney general of the United States Eric Holder for ensuring that the right to vote, the fundamental pillar of our democracy is protected for all American citizens," said Advancement Project co-director Penda Hair in a statement.

The intervention of the U.S. Department of Justice came the same day that Florida officials were trying to get another federal agency to help the state verify the citizenship status of thousands of voters.

Secretary of State Kent Detzner wants the U.S. Department of Homeland Security to let Florida have access to an immigration database maintained by the federal government.

"I hope you will understand the importance of making sure the vote of an eligible voter is not diminished by the vote of ineligible voter and provide my department the access it needs," Detzner wrote to Secretary Janet Napolitano.

A Department of Homeland Security official said Thursday that the federal agency is aware of Florida's request but that there a "number of legal and operational challenges" to granting the state access.

Detzner in his letter said that while Florida's initial list was "credible and reliable" he acknowledged that his department's ability to "validate a person's legal status as up to date was limited." The first list was drawn by comparing driver's licenses to voter registration lists. The Department of Highway Safety and Motor Vehicles initially planned to double-check its information with the federal database but has since been told that is not permitted.

Even without access to the federal database Cate had said the state is likely to circulate additional names to election supervisors in the weeks ahead.

But some election supervisors are already saying that they will ignore any additional names given to them by the Florida Department of State.

"It's illegal under federal law and I'm going to follow the law," said Leon County Supervisor of Elections Ion Sancho.