CHARLOTTE, N.C. — The former head of North Carolina’s Republican Party formally pleaded guilty in federal court Wednesday for his role in one of the state’s biggest political corruption cases. Former GOP Chairman Robin Hayes agreed to plead guilty to lying to federal investigators. He faces up to six months in prison, though prosecutors are likely to ask for less time. No sentencing date has been set. Hayes, 74, is a Concord native who served in Congress for a decade. The former lawmaker also once ran for governor. He was one of four men indicted in March on multiple charges...