PHOENIX - Attorney General Tom Horne accused the Obama administration Tuesday of trying to thwart Arizona's voter-ID laws in a bid to get more illegal immigrants to the polls - presumably to cast ballots for the president and Democrats.

Horne acknowledged a brief filed by the Department of Justice in a case to be heard next month by the 9th U.S. Circuit Court of Appeals. The U.S. filing argues that Arizona's law requiring proof of citizenship to register is pre-empted by federal law. But Horne, a Republican, said he sees something more sinister.

"I think the motive is that the more illegals that vote, the better the Obama administration thinks it will do," he said.

As proof, Horne pointed out that the Justice Department didn't file its friend-of- the-court brief until just last week, just two weeks before the case is set to be heard and nearly three years after the Mexican American Legal Defense and Education Fund and others first challenged the law.

A Department of Justice spokeswoman dismissed Horne's questions, saying the arguments in the legal brief speak for themselves.

At the heart of the fight is a 2004 voter-approved law that requires presentation of certain documents proving citizenship before someone can register. Another provision of the same law, not at issue here, mandates identification before casting a ballot.

The lawsuit contends that violates the National Voter Registration Act, which identifies what states can and cannot require before someone can vote in federal elections.

A trial judge ruled against the law's critics. But last year, in a divided opinion, a three-judge panel of the 9th Circuit ruled the law invalid because of the conflict with the National Voter Registration Act.

That led to the decision to ask for review by a full 11-judge panel of the court. Horne, who said he will argue the case personally, said this is more than an academic question.

"Illegals are voting, and they shouldn't be voting," he said. "Nobody that I've talked to, regardless of political persuasion, can understand how a court can tell us that we can't make sure that people who vote are citizens."

Horne said there was evidence presented when the case went to trial that illegal immigrants had registered to vote.

"Normally, the way they catch people is they get a jury summons and they swear under oath that they're not citizens," he said. "But they're already registered to vote."

But MALDEF attorney Nina Perales said the evidence presented was that some people who are not citizens did, in fact, register to vote. But she said it would be wrong to call them "illegals."

"I know that some citizens in Arizona love to collapse those terms and make every legal permanent resident immigrant into a so-called illegal immigrant," Perales said. "So if that's what he told you - that there was evidence in this case that there were illegals registered to vote and voting - that is a falsehood."

Perales said there was testimony of "scattered incidents" of people who thought they were eligible to register to vote, did register and only found out later that they were not eligible.

Horne, however, said in one year there were about 200 incidents reported of people who were not citizens having registered to vote. "And about 10 were prosecuted," he said.

Horne said there is no reason for the Obama administration to insert itself into the fight, other than for the political goal of "enabling illegal aliens to register to vote."

"What we are asking for is not burdensome at all," he said of the proof of citizenship requirement.

Horne said 90 percent of Arizonans have a driver's license or a state-issued ID card for those who do not drive, both of which are now recognized as proof of citizenship.

He also said all naturalized citizens have a certificate with a number of its own, which also can be listed on the registration forms.

"The burden is minuscule," Horne said. And he said even the U.S. Supreme Court has recognized there are benefits in ensuring that only those legally entitled to vote are casting ballots.

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