Microsoft (NSDQ: MSFT) CEO Steve Ballmer may be building a case for backing out of the offer for Yahoo (NSDQ: YHOO), or so suggests WSJ ... Ballmer told the paper it’s a matter of scale: “The question is, is there a better way to get to scale more quickly?” Microsoft has the technology but not the scale in customers and advertisers yet to be truly competitive with Google; doing it sans Yahoo lengthens the timeline. As for any sense of a decision coming from yesterday’s board meeting, Ballmer stayed oblique: “With the right circumstances it’ll happen. Without the right circumstances it won’t happen.”

Is there an alternative acquisition? “Look at all the properties on the Internet—everything on the Internet. There’s really only five or six that really have any scale. Worldwide, you’d maybe get seven or eight.” In addition to Yahoo and Microsoft’s own MSN, he listed MySpace, Facebook, AOL (NYSE: TWX) and Google (NSDQ: GOOG).

The interview followed a staff meeting, where Ballmer told Microsoft employees that “I will go to what I think it’s worth if that gets a deal done” but “I won’t pay a dime above” what it’s worth.

WSJ: “… his remarks to employees and in the interview appear to be an effort to build a case for backing away from the deal. Mr. Ballmer shrugged off the perception that the bid is a sign that Microsoft’s attempts to build its own online services and ad business wasn’t working.”