The meaning of the english idiom “Cream rises to the top”:
“A good person or idea cannot go unnoticed for long, just as cream poured in coffee or tea eventually rises to the top.”
Bachmann, Perry, Cain and now Newt has been notice and and have been found wanting.
Cain and Newt are still very much at the top of the game, although Cain might be on the way down.