The Obama administration on Monday blocked a new law in Texas that requires voters to show a photo ID, drawing fierce criticism from Republicans who say the move was aimed at boosting President Obama’s reelection prospects.

The Justice Department said that the law disproportionately harms Hispanic voters.

“Even using the data most favorable to the state, Hispanics disproportionately lack either a driver’s license or a personal identification card,” Thomas Perez, head of the Justice Department’s civil rights division, wrote in a letter to Keith Ingram, director of elections for the Texas secretary of state.

The action follows a similar move in late December to block a voter ID law in South Carolina that federal officials said adversely affects black voters.

The challenges are part of an escalating national legal battle over voter ID laws that has become more intense because it is an election year. Eight states passed voter ID laws last year, and critics say the new statutes could hurt turnout among minority voters and others, many of whom helped elect Obama in 2008. But supporters of the measures — seven of which were signed by Republican governors and one by an independent — say they are needed to combat voter fraud.

Texas Gov. Rick Perry (R), who signed his state’s measure last year, said the Justice Department’s decision is an example of Obama’s “continuing and pervasive federal overreach.”

“The DOJ has no valid reason for rejecting this important law, which requires nothing more extensive than the type of photo identification necessary to receive a library card or board an airplane,” Perry said in a statement.

Texas and South Carolina have filed lawsuits in U.S. District Court in Washington to overturn the federal action. Both suits now rest in federal court, and how fast the system moves will determine whether the matters are resolved before the general election in November.

Blocking the voter ID laws represents the first time the government has rejected such statutes in nearly 20 years and is in line with efforts by Attorney General Eric H. Holder Jr. to make the enforcement of civil rights a centerpiece of his tenure.

“The reality is that — in jurisdictions across the country — both overt and subtle forms of discrimination remain all too common and have not yet been relegated to the pages of history,” Holder said in a recent speech.

The Justice Department has the power to block the South Carolina and Texas laws under Section 5 of the 1965 Voting Rights Act, which requires 16 states or parts of states with a history of discrimination to receive federal approval before changing their voting laws. The states must prove to the federal government that the new statutes would not discriminate against minority voters.

The Texas law requires voters to present one of the following documents: a state-issued driver’s license or identification card, a military photo ID, a passport, a U.S. citizenship certificate with a photo, or a concealed-carry handgun license.

In his letter to Ingram, Perez said that, according to the state’s own data, Hispanic voters in Texas are much more likely than a non-Hispanic voters to lack the required identification.

Civil rights groups praised the Justice Department’s action.

“Texas’s voter ID law would prevent countless Latinos, African Americans, elderly citizens and others from casting their ballot,” said Katie O’Connor, a staff lawyer with the American Civil Liberties Union’s Voting Rights Project. “We’re pleased the Department of Justice has recognized the harms this discriminatory law would have on people’s fundamental right to vote.”

NAACP President Benjamin Todd Jealous said the challenge ensures that “the integrity of our election process remains intact.”

But supporters of the voter ID laws criticized the federal action as “purely political.”

“Today’s decision reeks of politics and appears to be an effort by the Department of Justice to carry water for the President’s reelection campaign,” Sen. John Cornyn (R-Tex.), a member of the Senate Judiciary Committee, said in a statement.

Hans von Spakovsky, a senior legal fellow at the conservative Heritage Foundation, accused the Justice Department of playing “statistical games” and said the decision was based on “ideology.”

“The Texas law isn’t any different than the Georgia and Indiana voter ID laws, and both of those laws have been in place more than five years,” he said. “Turnout of Hispanics and blacks went up dramatically after voter ID laws went into place. The Justice Department is ignoring all that.”

Georgia’s law required and received federal approval under the George W. Bush administration. The decisions are made on a state-by-state basis.

Laws approved last year in Mississippi and Alabama also require federal approval but have not been submitted to the Justice Department.

It is unclear whether the four states that passed voter ID laws that are not subject to the Voting Rights Act requirement — Kansas, Rhode Island, Tennessee and Wisconsin — will face federal challenges. Justice lawyers could file suit under a different provision of the act, but the department has not indicated whether it will do so. Wisconsin’s law has been blocked by two state judges.