The US’s support to Israel has not always existed, nor has it been unconditional. From 1948 to 1967, the assessment of the US State Department was that Israel would not withstand the threats to its existence, so they prioritized their relations with the Arab countries. Presidents George Bush (Sr.), Jimmy Carter or Barack Obama have been reticent towards Israel or have shown a certain hostility in many topics.
The influence of the North American Jews is important, especially during elections, as Jews donate 70% of the funds raised by the Democratic Party and 30% to the Republicans. Jews usually vote for the Democrats (over 70% since the 1920s), a party that during the recent years has developed a harsh anti-Israel branch. One of the most influential organizations is AIPAC (American-Israeli Public Affairs Committee). Many of the 5,000,000 Jews belong to different pro-Israel lobby organizations, competing with other anti-Israel lobbies. The US has other allies in the Middle East, and some of their relations (with Saudi Arabia) have created friction with Israel. However, Israel is still more predictable and trustworthy, being a vibrant democracy, and is an alternative in a highly unstable zone. At present (2019), the vote of the 70 million Christians in the US belonging to the Bible Belt (Evangelic Christians) is more determining than the Jewish vote. The economic support of the US to Israel is larger than other countries, but unlike the 70s decade, it has ceased to be determining for its economy. The US strategic support is still a survival issue for Israel, not only because of the immediate threats, but also because of the diplomatic estrangement it must face, and because of the influence of the US on some neighboring countries.