As Republicans move on to the South Carolina primary, the state’s Republican governor, Nikki Haley, has announced plans to sue the Obama administration for blocking a recent law requiring voters to show photo IDs at the polls. The Justice Department says the law violates the Voting Rights Act, citing data showing minority voters were about 20 percent more likely to lack acceptable photo ID required at polling places. On Tuesday, Haley said she would challenge the law as part of a push-back against what she called the federal government’s “war on South Carolina,” which she said has included the blocking of the state’s new immigration restrictions and a labor challenge to a Boeing assembly plant.