Yesterday I wrote about the influence of the Israeli lobby on Congress, referencing that Pelosi didn't have the votes to tie Bush's hands on Iran.
If you're interested in AIPAC and it's influence on Congress, go read this.
There is an accompanying video of a debate between those who support Israel and the authors of the article which would give a fantastic overview of the situation.
I'm not necessarily an advocate of abandoning Israel. But I do think we bend over too far in Israel's favor. The conservative hawkish government in Israel is a huge impediment to solving some of the key, festering problems in the middle east. Until the U.S. takes an even hand in it's role the problems will never be solved. And AIPAC is key to understanding the coupling/decoupling of Israeli influence in American politics.