About 3 to 4 million voters affected by existing voter ID laws face enormous difficulties to get to the polls, according to a new study by the Brennan Center for Justice.

The study says 1 in 10 voters in states with those laws - Alabama, Georgia, Indiana, Kansas, Mississippi, Pennsylvania, South Carolina, Tennessee, Texas, and Wisconsin - fall below the federal poverty line and live more than 10 miles from the government office that issues identifications, often without a vehicle.

"What we found really undercuts the claim by many proponents of these laws that eligible voters can easily obtain an ID to vote," one of the study's authors, Keesha Gaskins, said at a Wednesday press conference. "Our findings demonstrate that there will very likely be a significant number of citizens who will struggle to obtain a photo ID due to structural barriers."

The 10 states in question, the study says, are of particular importance in the 2012 presidential election, since they will provide 127 electoral votes, nearly 50 percent of the 270 needed to win the election.

The study says 500,000 eligible Latino voters and 1.2 million black voters live more than 10 miles from the nearest office where they can get an ID, and in several states, Gaskins said, less than half of those offices are open more than twice a week, and none of them are open weekends.

Last week, the U.S. Justice Department argued in federal court that Texas' law was designed to restrict voting opportunities for the state's growing black and Latino communities. A decision on that case is expected to be handed down in August.

Based on the study's findings, Texas would be particularly affected by a voter ID law: according to the study's other author, Sundeep Iyer, there are only two offices issuing IDs for 134,000 eligible voters - more than half of them Hispanic - in 32 counties in West and South Texas that are open more than twice a week.

"You can't divorce the voter ID law itself from the difficulty in obtaining [an] ID," Iyer said. "Some people are just gonna have a really difficult time obtaining voter identification, and I think that speaks very strongly against the merits of these laws."