Federal Liberal leadership campaign organizers say members of a close circle of political advisers to Ontario Premier Dalton McGuinty, who announced his resignation on Monday evening, are scouting out organizers for a potential bid by Mr. McGuinty for the federal party leadership, but three MPs say Mr. McGuinty’s candidacy is unlikely, in part because Liberal MP Justin Trudeau is “too far ahead” and also because Mr. McGuinty has already stated he is leaving his provincial position because the Ontario party needs renewal.