Rep. John Conyers on Tuesday announced his retirement from Congress while in a Michigan hospital bed, saying he is endorsing his son, John Conyers III, for the seat he has held for more than a half century amid growing sexual-misconduct allegations. “I’m retiring today,” the 88-year-old Michigan Democrat said in a phone interview with a local radio station from a Detroit hospital, where he has been since last month after experiencing chest pains. “I want everyone to know how much I appreciate [their] support.” Conyers, the longest-serving congressman, made the decision two weeks after sexual harassment allegations first surfaced and...