Sen. Dianne Feinstein says she thinks Hamid Karzai (HAH'-mihd KAHR'-zeye) "is such a cipher."
The California Democrat tells CNN's "State of the Union" that Karzai is "so much the victim of what thought occurs to him right at the moment based on some anger that he feels about something that may not even be related."
Karzai says he'll leave the matter to the next president after April elections.
The US has said it will plan to withdraw all troops after 2014 if he doesn't sign promptly, and a signed deal is needed to enable US troops to train Afghan forces.