In a speech at the NAACP National Convention in Houston, Holder said the Civil Rights Division had filed a record number of cases and the White House was committed to defending voting rights.
"The Justice Department's efforts to uphold and enforce voting rights will remain aggressive," Holder said in his prepared remarks. "And I have every expectation that we'll continue to be effective."
In remarks that had not been included in his prepared speech, CBS News reported Holder -- referring to a law signed this year by Texas Gov. Rick Perry -- criticized a provision that "concealed handgun licenses would be acceptable forms of photo ID, but student IDs would not."
"Many of those without IDs would have to travel great distances to get them, and some would struggle to pay for the documents they might need to obtain them," he said. "We call those poll taxes."
A federal appeals court in Washington Monday began hearing a Justice Department challenge of the Texas voter ID law. The Justice Department has refused to certify the new law, a step required by the Voting Rights Act when Texas changes election procedures.
Holder told the NAACP audience Tuesday his department opposes the Texas law, in part because it would unfairly affect minority residents who may not have the money or wherewithal to apply for a driver's license or state ID. He cited a nationwide study that concluded while 8 percent of voting-age whites lacked an official photo identity card, 25 percent of Africa-Americans lacked the necessary ID.
"We will not allow political pretexts to disenfranchise American citizens of their most precious right," Holder said.
"The Justice Department has initiated careful, thorough, and independent reviews of proposed voting changes -- including redistricting plans, early voting procedures, photo identification requirements, and changes affecting third party registration organizations -- in order to guard against disenfranchisement."