In his negotiations last week with the Israelis and Palestinians, Secretary of State John Kerry must have reminded them that it has long been clear that the sympathies of the American public are more favorable to Israel than to their adversaries in the Arab-Israeli conflict. For many years, the Pew Research Center has been conducting national surveys on this issue. The latest one, in March 2013, reaches the same conclusion as previous surveys, finding that 49 percent of those consulted sympathized more with Israel, while 12 percent sympathized with the Palestinians.

What is new, however is the growing difference between Republicans and Democrats in their attitudes to Israel. Today, 66 percent of Republicans say they sympathize more with Israel than with the Palestinians, compared with 49 percent of independents and 39 percent of Democrats. This compares with a 1978 survey that showed the relative support by the three of 49 percent, 45 percent, and 44 percent.

Nevertheless, all political groups in the U.S. say they sympathize with Israel more than with the Palestinians. Republicans and conservatives are the strongest supporters, with Democrats, liberals, and leftists the least supportive. Only 2 percent of conservative Republicans favored the Palestinians compared with 22 percent of leftist Democrats, only 33 percent of whom favor Israel. Though there have been fluctuations, the overall support for Israel has declined since 1991 when it was 74 percent to 49 percent at present. Yet, in the Gallup poll on World Affairs of February 2013 when Americans were asked their opinions on 22 countries, Israel ranked seventh with 66 percent favorable and 29 percent unfavorable. The countries ranked higher than Israel were Canada, Britain, Germany, Japan, France, and India. The most negative rankings were those of the Palestinian Authority, Syria, North Korea, and, at the very bottom, Iran.

The gap between Republican and Democratic sympathy for Israel has grown as Republican support for Israel has increased while Democratic support has remained more or less the same. In 1978 the gap was about five points; in 2013 it is 29 points. Differences also exist within the parties. Among Republicans the more conservative are more favorable than moderates to Israel. Among Democrats, 46 percent of the moderates were favorable compared with 33 percent of the more leftist. Among Independents, support for Israel is 47 percent compared to 13 percent for the Palestinians.

Other differences in sympathy relate to religion and age. One significant factor is that white evangelical Protestants are more supportive of Israel than are members of other religious groups. The latest survey showed that 72 percent of the evangelicals sympathized more with Israel than with the Palestinians. This is compared to 37 percent of white mainline Protestants and 59 percent of white Catholics who sympathize with Israel. Yet even these last two groups register little sympathy with Palestinians; the support by white mainstream Protestants is 13 percent, and by white Catholics 6 percent. Of the country's religious groups, the white evangelical Protestants, with 46 percent, had by far the highest percentage to hold the belief that the U.S. has not supported Israel enough. Differences among the age groups are considerable. The largest proportion of those supporting Israel are those in the age group 50-64, who register at 59 percent, while the lowest is in the 18-29 age group at 36 percent.

Political events have already shown the increasing gap between the two major U.S. political parties on Israel. Political differences became apparent in comments about Israel's response in November 2012 to rocket attacks from Gaza. While 74 percent of Republicans supported the Israeli response, only 40 percent of Democrats, and 59 percent of Independents, did so. Another was the strong demonstration by some of the delegates at the Democratic National Convention in Charlotte in 2012 against the proposed pro-Israeli language in the party platform.

The conclusion must be that the leftist trend, and the increase of minority groups among the Democrats makes the traditional bipartisan support for Israel less automatic than it has long been. If it is true that not all Democrats are anti-Israeli, it is also true that most anti-Israelis are Democrats.

For some this has been puzzling but this largely results from the reality that domestic issues are more important than foreign issues for U.S. voters in general and for Jews in particular. Jews, following Democrats, are more likely than other U.S. citizens to support issues such as civil rights, separation of church and state, social security, health care, feminism, and gay rights. The Jewish vote for presidential candidates has always, even before the appearance of Franklin D. Roosevelt, been strongly Democratic, except for Jimmy Carter in 1976, and though it declined from 78 percent in 2008, it still favored Barack Obama in 2012 by 69 percent.

It would be too extreme to argue that Jews dissociate themselves from concern with Israel because of psychological self-hatred. Israel is simply not at the center of their lives, nor are Jews single-issue voters. It is evident that Jews vote Democratic for economic and social reasons and that Israel, and even general foreign policy, has a low priority in their decision. Those who vote Democratic are explicitly or implicitly calling for what they regard as general social justice and Tikkun Olam (Repairing the World) rather than being concerned for the particular country, Israel. Only 4 percent of the Jewish vote thought that for them Israel was the most important factor, and only 20 percent thought it important at all.

Democrats, particularly those who are more on the left , have tended to adopt the Palestinian narrative of victimhood articulating their grievances and their oppression by the Israelis. This attitude has been made familiar by opinion makers, by the mainstream churches, and by many in the media and in the academic world.

A time-honored political maxim is that officials, particularly legislators, respond to those with high salience, taking into account the opinions of the strongest voices. Until recently those voices have mainly been the voices of pro-Israeli supporters. Other points of view less supportive of Israel are now increasingly being voiced, as the surveys show. Pro-Israeli supporters must reach out to both younger and secular Americans who are likely to vote Democratic. At a time when the Arab countries in the Middle East are in a turbulent state and Islamist forces and Iran present a danger to the world, it is incumbent on supporters of Israel, by raising their voice on behalf of Israel, to make clear the nature of the fallacious Palestinian narrative, which makes a peace settlement less probable.