WASHINGTON â€” The Obama administration on Friday blocked a new South Carolina law that requires voters to have photo identification because of concerns it would hurt minorities' ability to cast a ballot.

Republican Gov. Nikki Haley in May signed into law a measure that says voters must show a driver's license, passport or military identification along with their voter registration card in order to vote.

Under the law, anyone who wants to vote but does not have a photo identification must obtain a new voter registration card that includes a photo. A birth certificate or passport can be used to prove identity.

The Justice Department said the requirement could harm the right to vote of tens of thousands of people, noting that just over a third of the state's minorities who are registered voters did not have a driver's license needed to cast a ballot.

"The state's data demonstrate that non-white voters are both significantly burdened" by the law and "disproportionately unlikely to possess the most common types of photo identification" needed, Thomas Perez, head of the Justice Department's civil rights division, said in a letter to the state.

The state can appeal the decision at the Justice Department or in federal court. Attempts to reach a spokesman for Haley were not immediately successful.

Democrats have described the law as a "voter suppression" effort against minorities who historically do not always have photo identification cards. Republicans countered that their goal was to prevent voter fraud.

However, Perez said that South Carolina's submission to the Justice Department did not offer any evidence of voter fraud that was not addressed by existing law and that "arguably could be deterred by requiring voters to present only photo identification at the polls."

The Justice Department said plans by state officials to provide exemptions to the photo identification requirement were incomplete and vague. The state also has not finalized education and training materials.

If those issues were addressed, the Justice Department said the state could resubmit its plans and officials would consider revising its position.

The Justice Department move marks an escalation in the battle between the Obama administration and Republicans who control the legislatures in some states just 11 months before the 2012 presidential and congressional elections.

Obama lost South Carolina in the 2008 presidential race by a nine-point margin to his Republican opponent Sen. John McCain.

Under the landmark 1965 Voting Rights Act, certain states like South Carolina must seek approval from the Justice Department or the federal courts for changes made to state voting laws and boundaries for voting districts.

U.S. Attorney General Eric Holder earlier this month said his team was reviewing changes to voting laws in other states including Florida and Texas and will challenge any that are discriminatory in violation of the federal voting rights law.

"The reality is that — in jurisdictions across the country — both overt and subtle forms of discrimination remain all too common," he said in a speech in Austin, Texas.

The Justice Department has also challenged a new election map drawn by Republicans in Texas, arguing that it does not fairly represent the exponential growth in Hispanic voters. Hispanics largely have supported Democrats in past elections.

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