An interesting essay on the Left and their views of Israel:

These views are also mainstream for most Americans, which is why support for Israel routinely runs three to five times the support level for the Palestinians in every public opinion survey that is taken. In the House, the tendency to use the redistricting process after every census for incumbent protection, has led to the creation of a very large number of safe seats, and very few competitive ones (perhaps 10-15% of the total). This has given incumbents the ability to be less mainstream in their views on this issue and others. The growth in the Arab and Muslim population in America, and the creation of more districts with high percentages of African American voters, are both elements that could create more House members sympathetic to the Palestinian cause, since both African Americans, as a group, and Arabs and Muslims, to a much larger extent, are less sympathetic to Israel than the general population. In any case, it would be hard to point to any individual member of Congress today and say that he or she hates Israel.

The left in this country includes large numbers of academics, journalists, human rights activists, environmental and animal rights activists, entertainers, and some church groups, women?s groups, racial advocacy groups and unions. There are also liberals who are members of these same groups. I distinguish between leftists and liberals by one key test: how they feel about the country in which they live. If you tend to regard America as a primarily flawed, evil, unjust, racist country (or at least when Republicans are running it), and most importantly, believe that the US is the primary threat to world peace internationally, then you are a leftist, and not a liberal. Of course, many leftists are perfectly happy to be living here, amidst all their complaints about the country, and regrettably all too few Hollywood artists carried through with their threat to leave the country after the 2000 election.

WHY DOES THE LEFT HATE ISRAEL?
I believe there are several reasons:
1. It is an easy way to express one?s hatred for America.
2. Israel is viewed as an outpost of colonialism , and an active practitioner of it.
3. Israel is a western nation, and hence can be judged by the left. Israel is not protected by cultural relativism, as the Arabs are.
4. Leftist Christian churches can escape any lingering guilt about the Holocaust, by turning Israel into a villain. Some leftist churches hate Israel because they think this will help protect their members in the holy land- in other words they feel threatened.
5. Ferocious Muslim hatred of Israel and the Jews reinforces the natural cowardice of many on the left who go along with the Muslims to stay out of their line of fire.
6. Jewish leftists are prominent in the anti-Israel movement. This opens the floodgates for everybody else.
7. Israel is attacked because the secular left is appalled by the influence of religious settlers and their biblical connections to the land of Israel, and by the support for Israel by evangelical Christians, and Christian Zionists.
I believe there are several reasons:
1. It is an easy way to express one?s hatred for America.
2. Israel is viewed as an outpost of colonialism , and an active practitioner of it.
3. Israel is a western nation, and hence can be judged by the left. Israel is not protected by cultural relativism, as the Arabs are.
4. Leftist Christian churches can escape any lingering guilt about the Holocaust, by turning Israel into a villain. Some leftist churches hate Israel because they think this will help protect their members in the holy land- in other words they feel threatened.
5. Ferocious Muslim hatred of Israel and the Jews reinforces the natural cowardice of many on the left who go along with the Muslims to stay out of their line of fire.
6. Jewish leftists are prominent in the anti-Israel movement. This opens the floodgates for everybody else.
7. Israel is attacked because the secular left is appalled by the influence of religious settlers and their biblical connections to the land of Israel, and by the support for Israel by evangelical Christians, and Christian Zionists.

Read it all. It's long but very well thought out.