There is broad, bipartisan support for Israel in the United States. ~Greg Scoblete 
No country favors taking Israel’s side, including the United States [bold mine-DL], where 71 percent favor taking neither side. ~WorldPublicOpinion.org 
The Gallup survey asked  respondents whether their “sympathies” are more with Israelis or Palestinians. Of course a vast majority will say that their sympathies are with the Israelis. The result would necessarily be lopsided because the question is bound to elicit such a result. The question isn’t being asked in a vacuum, and it isn’t actually a question about what U.S. policy ought to be.
Leaving aside existing cultural and religious reasons for such sympathy, the vast majority of media portrayals of the conflict encourage such sympathy. Our political class is virtually unanimous in casting the conflict in very simple terms that reinforce this sympathy. Are we more likely to sympathize with the modern, Western, industrialized, democratic nation-state whose people’s history is related to ours or with a stateless refugee nation of Arabs whose members mostly belong to a religion a large number of Americans regard unfavorably? The high degree of sympathy the public has now is the product of decades of advocacy, rhetoric and political pressure in our domestic debate almost entirely on one side of a foreign conflict. Pro-Israel sympathy was not always as great as it is now. Not so long ago, it used to be much lower.change_me
The Gallup numbers show us this. If we look at the late ’80s on their graph, we see that just 37% sympathized with Israel, 15% sympathized with the Palestinians and 49% sympathized with neither side. As recently as 1997, the “neither” result was 54%. We do see sympathy for Israel spike in times of conflict. Before and during the Gulf War, the sympathy for Israel figure shot up to 64%, it rose during the second intifada, and after 9/11 over the last eight and a half years it has risen steadily to its current level. However, during the late ’80s and for much of the ’90s the “broad, bipartisan support” Scoblete points to in the recent survey was not there. Pro-Israel sympathy has commanded a majority of the public for less than half the time in the last 22 years, but it has been the constant, default position of virtually every national politician for at least that long.
In fact, if we distinguish between sympathy and actively wanting to take Israel’s side, real support is still actually much more limited. If we believe the WPO survey, there is definitely a difference between broad sympathy and the kind of support for Israel that the U.S. actually provides. According to the WPO survey, just 21% favor taking Israel’s side in the conflict and 71% prefer taking neither side. That suggests broad, probably bipartisan support for disentangling ourselves from the conflict all together. It also means that U.S. policy on this question does not simply flow from the will of the people. This 21% is the real constituency for current U.S. policy. This is a sizeable constituency that has effectively advocated and organized to make a one-sided approach to the conflict practically unquestionable in domestic policy debates. They and the policies they advocate do not represent the broad majority of Americans, even though a broad majority of Americans is now much more favorably disposed towards Israel than they once were.