Is Obama lying if he makes a statement/promise, then cirstances change in a way that he has no control ove?

Note that I am not taking up for Obama or any of the falsehoods that have transpired during his presidency. I happen to believe that if he chooses to make promises on his own, he should never make any statement or promise when there is ANYpossibility that cirstances could change in such a way that he will appear to have lied. However, it is one thing to lie outright and quite another to do the aforementioned, and the latter is true of most instances where people claim that Obama lied. For example during his campaign Obama claimed that he would not hire lobbyists if elected. Once he became elected, however, there came a need for him to do this among other things to thwart mounting pressure from GOP regarding his stimulus, healthcare bill, e.t.c., none of which is his fault. It could be in this sense that the GOP is aiding in making him look like a liar. The point is regardless of wether he should have made gratuitous statements/promises in the first place, how can you say Obama was lying when things change after he made a statement that he has no control over?