Originally Posted by vassilipan

The consent that applies at a checkpoint is implied; by presenting yourself you are implying that you consent to a search of your person and property. TSA conducts an administrative search, which is an exception to the search warrant requirement. The inability to withdraw an implied consent also occurs with DUI cases - refusal to comply with a breath or blood test results in separate charges, so in reality you either comply or get arrested.

All of this will (and should) result in a test case somewhere. I believe a lot of weight will be given to a traveller's assertion that a certain "intimidation" factor is present at a checkpoint, and TSO's, to a great many people, are LEO's.