Sir Galahad

In Canada, it is often less difficult and certainly less contentious to run for party leadership from outside the party rather than from inside it.
Two examples --John Turner and Brian Mulroney, who built their campaign organizations and wrote their speeches while lunching at their clubs rather than scarfing a sandwich in the Parliamentary dining room and running back to the House for a vote. They did not have to endure the insular hothouse Ottawa atmosphere, the sneers of the press gallery, and the Cabinet back-stabbing that so damaged Paul Martin's relationship with Chretien and his supporters over that endless last year of Chretien's prime ministership.
So when we wonder why Jim Prentice is leaving now, perhaps it is because he expects the Conservatives will be looking for a White Knight someday soon.