Well. They do. All of them. They tell whatever lie they think they need to tell at the time to get elected. There is no fallout from it. If it starts to become an issue they either get the press on their side to ignore it or if the press is not on their side then they manufacture something to get the heat off.
Not to the point of saying they are going to COMPLETELY overhaul the healthcare system, or close a prison that houses hundreds of terrorists/war criminals. Those aren't the kinds of things they make "promises" about. They may say they will lower taxes, or enact some piece of legislation, but they don't express intentions of modifying whole chunks of the way our society or government functions.
"I did not say he would not lie. I just said he wouldn't lie that big." Come on. That is crap. There is no lie they will not tell to get elected. Once in power they will do what they need to to try and stay in power.
Which is EXACTLY my point. Someone wouldn't consciously and purposely lie about radically changing our way of life BEFORE they get elected, and then, by choice, NOT do so once they ARE elected.
That's the exact opposite of trying to stay in power.