Richard Perle himself said (it is on tape) that even remotely criticizing Israel in US is a political suicide, he did not even hide this fact. It is much easier for an Israeli politician to criticize Israel in knesset than for an American politician do the same in the congress, infinitely easier. Americans, including Clinton, is afraid of Israelis and AIPAC, super-afraid. However you will see that Bibi will carry on with the settlements because in the long term Bibi wants confrontation, the friction between Israel and US will burn Obama. There is 95% chance that Obama will lose the next election and things will be exactly as Bibi wants.
from the article: Peres: We want U.S. ties to return to positive state