Microsoft has been hard at work looking for a CEO to replace outgoing leader Steve Ballmer, but it looks like we'll have to keep waiting for the company's final choice. Despite a desire to have a new CEO ready to go by the end of 2013, the company has just admitted that its search will go on for the time being — the company expects its search to be complete in the early part of 2014. Microsoft board member John W. Thompson admitted as much in a blog post released today.

We identified over 100 possible candidates, talked with several dozen, and then focused our energy intensely on a group of about 20 individuals, all extremely impressive in their own right. As you would expect, as this group has narrowed, we’ve done deeper research and investigation, including with the full Board. We’re moving ahead well, and I expect we’ll complete our work in the early part of 2014.

Of course, finding a replacement for Ballmer isn't easy — Thompson notes that Microsoft has only had two CEOs in its history, so finding a third isn't something the company and its board will take lightly. We've heard details on a number of individuals rumored to be on Microsoft's short list for CEO, but a strong front runner hasn't emerged yet. Ford CEO Alan Mulally seemed to be at the head of the pack, but Ford recently reaffirmed his intention to stay with the automaker through 2014.

Another rumored candidate, Qualcomm COO Steve Mollenkopf, seemed like a natural choice — but he's now off the board, as he's slated to take over as Qualcomm CEO on March 4th. Of course, it sounds like there are a number of other candidates being vetted beyond those whose names have leaked out in public, so it's entirely possible that the company is just being cautious in its vetting process. There's no doubt that whoever takes over for Ballmer will have some big shoes to fill.