The presidential campaign of former Gov. Mitt Romney of Massachusetts is scheduled to announce the endorsement of Representative Cynthia M. Lummis of Wyoming on Monday morning, adding a Tea Party voice to its chorus of Congressional endorsements. Ms. Lummis, who will serve as Mr. Romney’s Wyoming campaign chairwoman, is a solid fiscal and social conservative, and the Romney campaign hopes her support will underscore the already growing narrative that conservatives are rallying around Mr. Romney. “Governor Romney’s experience as both a chief executive and conservative businessman makes him highly qualified to lead our nation at this time — a time...