A full-scale biography of Senator John Kerry, now clearly the leader for the Democratic presidential nomination, is being rapidly written by three writers from the Boston Globe who have followed his career closely from the start. They are Michael Kranish, Brian Mooney and Nina Easton, and Public Affairs will offer their book as a trade paperback as soon as mid-April; the acquiring editor is Robert Kimzey. The book is an expansion of an admired series about Kerry that appeared in the newspaper and it will be called John F. Kerry: The Complete Biography by the Boston Globe Reporters Who Know Him Best. It will be sufficiently up-to-date to trace the astonishing turnaround in Kerry's fortunes that has made him the Democratic front-runner in early voting this year.