The Department of Justice filed a formal lawsuit against the state of Florida to head off the state's plan to purge ineligible voters from its rolls.

It's the latest salvo in an ongoing legal battle, as the DOJ claims that Florida's attempts to remove ineligible voters violates a federal law that's meant to prohibit such purges within the 90-day period before an election for federal office.

"The Department of Justice has an overriding interest in protecting the rights of eligible citizens to register and vote free from unlawful burdens, while at the same time ensuring that ineligible persons do not register and vote in federal elections in violation of the law," said Thomas E. Perez, assistant attorney general for the Justice Department's Civil Rights Division. "The department is committed to enforcing the National Voter Registration Act so that these objectives are met."

The DOJ's lawsuit seeks a court order declaring that Florida has violated the law and calls on the courts to keep the state from continuing with the voter purge program.

Florida filed its own lawsuit yesterday against the Department of Homeland Security, claiming the federal agency illegally restricted access to information on people who might not be eligible to vote.

Both lawsuits, along with one filed by the Florida ACLU against the state, ensure that the voter registration and removal issue will remain a contentious one up to the November elections.