WASHINGTON — John Edwards, the North Carolina Democrat making a second bid for the presidency, announced late Wednesday night that he would hold a news conference Thursday, a day after he and his wife, Elizabeth, visited Mrs. Edwards’ doctor to assess her health following her recovery from breast cancer. Mrs. Edwards, in a brief interview from her home in Chapel Hill, said she and Mr. Edwards would discuss her health at the news conference, but she declined to elaborate. “I’m still here,” she said. Jennifer Palmieri, communications director for the Edwards campaign, said that she would not provide any details...