As kendall pointed out: "Many people can not tell the difference between a person lying and changing his/her mind. They are not the same.

You can't lie about future events. You can lie about your intentions, but that is a different matter. "I will do so-and-so if elected" isn't a lie even if you don't do it, it's an unfulfilled prediction, Just so long as you actually intend to do so-and-so at the time you say it. Of course it is still a broken promise.