The basic reason why there is no such thing as "the will of the people" is that there is no people to have a will.
I don't know enough about the Middle East and foreign policy to take a position on the propriety of moving the United States embassy to Jerusalem. I now admit that, contrary to what I once thought, foreign policy - relations with foreign Leviathans - is a distinct and justifiable field of analysis and government action.
On general principles of law and reason, the treaties, so called, which purport to be entered into with other nations, by certain persons calling themselves ambassadors, secretaries, presidents, and senators of the United States, in the name, and on behalf, of "the people of the United States," are of no validity. These so-called ambassadors, secretaries, presidents, and senators, who claim to be the agents of "the people of the United States," for making these treaties, can show no open, written, or other authentic evidence that either the whole "people of the United States," or any other open, avowed, responsible body of men, calling themselves by that name, ever authorized these pretended ambassadors and others to make treaties in the name of, or binding upon anyone of, "the people of the United States." Neither can they show any open, written, or other authentic evidence that either the whole "people of the United States," or any other open, avowed, responsible body of men, calling themselves by that name, ever authorized these pretended ambassadors, secretaries, and others, in their name and behalf, to recognize certain other persons, calling themselves emperors, kings, queens, and the like, as the rightful rulers, sovereigns, masters, or representatives of the different peoples whom they assume to govern, to represent, and to bind. The "nations," as they are called, with whom our pretended ambassadors, secretaries, presidents and senators profess to make treaties, are as much myths as our own. ...
Our pretended treaties, then, being made with no legitimate or bona fide nations, or representatives of nations, and being made, on our part, by persons who have no legitimate authority to act for us, have intrinsically no more validity than a pretended treaty made by the Man in the Moon with the king of the Pleiades.
The basic reason why there is no such thing as "the will of the people" is that there is no people to have a will. The people is made of separate individuals who each has his own individual will. Indeed, Americans are divided on Middle East policy. And there is no way to aggregate these individual wills into a single social will except if all individuals are identical or if (as is the case in reality) some impose their wills on others or vote results cycle in an inconsistent way. Regarding inconsistency, opinion polls found that 81% of Americans think that the U.S government should keep or expand its commitment to Israel, while 39% think that it should decrease its military presence in, or completely withdraw from, the Middle East, and 64% that military aid to Israel should be decreased or stopped altogether.
A second reason is that the individuals who make up "the people" have precious little idea of what they are supposed to "have overwhelmingly supported." A voter has no incentive to learn about complex issues because his single vote can have no influence. A March 2016 Gallup poll asked Americans about the proposal to "recognize Jerusalem as the capital of Israel and move the U.S. Embassy to Jerusalem from Tel Aviv." Twenty-four percent agreed, 20% disagreed, and a full 56% admitted they "didn't know enough to say." The general lack of knowledge on international issues is well-known.
Finally, consider that when at most two-thirds of citizens participate in an election (it was 61.4% in the 2016 presidential election) and split their votes roughly equally, the winner incarnating "the will of the people" is supported by one-third of the electorate.
There are good arguments for democracy, provided that its power is limited. But democracy does not represent or create anything like a "will of the people."