Speculation over Microsoft Corps succession plans refocused on internal choices on Wednesday, a day after the leading outside candidate, Ford Motor Co CEO Alan Mulally, took himself off the list of potential CEOs at the worlds largest software maker. For months, Microsoft watchers had pegged Mulally as the odds-on bet to succeed Steve Ballmer as chief executive at the dominant producer of software for desktops and laptops, which has faltered in making the transition to the fast-growing mobile phone and tablet markets. It was unclear whether Mulallys withdrawal from consideration was his decision or Microsofts. While the companys intentions remained a guessing game, internal candidates now seemed the obvious ones, especially in light of comments by Microsoft about the importance of tech know-how for the top job. Sources familiar with the process have told Reuters that Microsoft is down to a handful of candidates, including insiders Satya Nadella and Tony Bates.