Clinton knows that she is currently freezing the field with the-door-remains-slightly-open statements like “I have no intention” to run for president. Having no intention to run is not even close to the same thing as ruling out the race. Words matter in politics and no one understands just how much better than Clinton.
She also knows that her ability to keep the race frozen in place has a shelf life and if she waits too long to decide she will lose a fair amount of the political goodwill she has built up in the party.
So, when does Clinton need to make a declarative pronouncement about her plans? It’s hard to pinpoint a particular date but it’s hard to imagine her being able to wait much beyond the 2014 midterm elections. At that point, the Iowa caucuses and New Hampshire primaries will be slightly more than a year(!) away, and the other men and women who want to run will be itchy to get the Clinton question answered. (For everyone not named Clinton, the sooner she makes up her mind, the better.)