Complex sentence: McKenna, a young lawyer representing Chatam in the legislature in his first term, ran as the underdog in a leadership race against party stalwart Ray Frenette who had served as interim leader from the disastrous 1982 election until the eve of the 1985 leadership race.
Split into simpler sentences: McKenna, a young lawyer representing Chatam in the legislature in his first term, ran as the underdog candidate in a leadership campaign against party stalwart Ray Frenette. Frenette had served as interim leader from the disastrous 1982 election until the eve of the 1985 leadership race.