Pawlenty's departure, Perry's entrance and stagnation among Gingrich, Santorum, Huntsman and the other hard-to-remember GOP candidates seem to indicate that the Republican nominee will emerge from a battle between Perry, Romney and Bachmann.
Marc Thiessen has a solid case for Perry in today's WaPo. Much will be decided for Perry in the next few weeks. If he flounders and disappoints expectations, voters will quickly look elsewhere. But he has the potential to rally a base divided between a lackluster resignation toward Romney and hesitant uncertainty toward Bachmann. Perry needs to thread the needle and poach supporters from both candidates - all the while representing himself as the GOP moderate between Romney's unreliable conservatism and Bachmann's uncompromising conservatism.
Romney and Bachmann are still in the fight because they emerged as leaders of the pack - Romney as the party's crown-prince and Bachmann as the hero of the people. Perry needs to define himself as something superior to both - and soon - if his star is going to rise as far as the nomination.