There are some polls that show roughly 35 to 60 percent of US voters backing the sale of arms to Israel, depending on demographics, but there is a very clear divide between Republican and Democrat support so it's disingenuous to say a candidate will lose more support than they gain because that depends on which candidate.
A lot of these polls also use loaded questions like "who is responsible for this conflict" with the two choices being Hamas and Israel, which doesn't really capture any of the nuance of the situation or represent the beliefs of the person answering the question.