I personally believe that most politicians do not or know in detail what it is they are supporting or approving. Their knowledge is purely a function of how does this legislation affect which voting block. What they know is also a function of who prepares the summary for them to have a cursory knowledge of what they are supposed to support or sign.

This is proven every single day when a politician states what he thinks the group (votes) in front of him wants to hear. Then the next day they walk back what they said or re-state what they said or the likes of Josh (the press secretary) merely goes on to say well that is not what he meant. Mean while the mission was accomplished right. They said what they wanted to say in front of the target group.

Politicians are on page two (maybe) of the list of Who Do You Trust.