Florida Gov. Rick Scott is defending his effort to prevent non-U.S. citizens from voting in his state after the Justice Department filed a lawsuit to stop him on Tuesday.

Scott told NPR's Michel Martin on Tell Me More Wednesday that after learning his state didn't verify the citizenship status of registered voters, he's trying to ensure that the ballots of U.S. citizens aren't diminished:

"What we've found is noncitizens voting, noncitizens registered to vote. I cannot sit here, as governor of this state, and not enforce our law. It's a crime and dilutes the right of U.S. citizens to vote."

Florida has been criticized for the way it identifies potential noncitizens, and local elections officials and others have found the results to be flawed.

The state says it has tried to verify the status of about 2,700 registered voters. So far, more than 500 of them have been identified as actual citizens. More than 140 have been identified as noncitizens, and about 50 may have unlawfully cast a ballot.

A Miami Herald report found that the list of potential noncitizens "disproportionately" includes minorities. Nearly 60 percent of the people flagged are Latinos, who make up 13 percent of Florida's active registered voters.

Scott says the state can't complete the verifications without gaining access to a federal immigration database. The Department of Homeland Security has refused Florida's request, saying the database isn't suitable for such a use.

Without the federal data, Scott says, Florida has been "forced" to match voter rolls against its own driver's license records.

On Monday, the state filed its own lawsuit demanding access to the immigration database.

"The statute says that the state has a right to use that database for voter registration. That's the law," Scott told Martin. "We'll make sure that we do it the right way. Not one U.S. citizen has been eliminated from the voter rolls. Not one."

Some critics accuse Scott, a Republican, of purging eligible voters to give his party an advantage on Election Day.

"First off, there's no voter purge," Scott told Martin. "This is not a Republican or Democratic or independent issue."

Florida has been one of the states most active in making controversial changes to its election laws and procedures; state officials say the measures are aimed at preventing voter fraud.

A federal judge recently struck down portions of a Florida law that tightened rules for third-party groups that register voters. The state also has been criticized for reversing rules that had made it easier for former felons to vote.

Since 2008, states across the nation, most of them led by Republicans, have changed election laws to restrict voter registration drives, scale back early voting periods or stop people from registering to vote on Election Day. All three practices had been credited with helping increase the turnouts of young and minority voters who helped elect President Obama in 2008.

The Brennan Center for Justice at New York University, which represented plaintiffs in the lawsuit over Florida's voter registration changes, found that such election laws have passed primarily in presidential battleground states.

The Justice Department has taken action to stop several such laws from being enacted, arguing that they could disproportionately prevent minorities from voting.

On Tuesday, Attorney General Eric Holder told a Senate committee:

"The question I think we have to ask ourselves, on both sides of the aisle, is 'Do we want to be the first generation to restrict the ability of American citizens to vote?' We have a bad history in that regard."

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