New laws in several states could require voters in the 2012 elections to show photo identification when they cast ballots. According to NPR, the tighter voting regulations "could affect turnout and influence general election results in battleground states."

Several states, including South Carolina, Mississippi, Texas, Kansas, Tennessee and Wisconsin, toughened voter identification requirements, NPR says. Proponents say the new laws will prevent election fraud while opponents say the measures will block ballot access for many voters.

The federal government could veto new photo ID laws in southern states that, under the 1965 Voting Rights Act, require Justice Department approval of changes in election laws. The Justice Department blocked South Carolina's photo ID law, according to NPR, "saying it would unduly harm thousands of minorities who don’t have identification." Gov. Nikki Haley said she will fight the Justice Department's decision, which could be reversed in federal court.

Photo ID laws in Mississippi and Texas also could wind up in federal court on appeal if the Justice Department rejects them, NPR says.

Currently voters in 31 states must show some form of identification, with 15 states requiring photo ID. Some states also passed laws that shorten early voting periods or prevent voters from registering on Election Day, according to NPR. The new measures could affect voters in key states for the 2012 presidential election.