Sometime in the early-to-mid-1990s, if memory serves, I read an interview with someone who had recently been elected to Congress on a promise to balance the federal budget and, he or she told the interviewer, had indeed immediately instructed the office staff to prepare a balanced budget that would eliminate the deficit by simply cutting foreign aid. The staff's response, said the newly elected Congressperson, came as a shock: Foreign aid was under one percent of spending, so even eliminating it entirely would make only a modest dent in the deficit, which at the time was running about 20 percent of the budget.
It ought to be shocking that someone running for Congress on the basis of a specific idea wouldn't take a few minutes to check whether the idea made any sense, but unfortunately most of us aren't very shocked at all. Appalled, maybe, but not shocked.
Anyway, foreign aid is still running about the same percentage of federal spending, and the subject is more complicated than its supporters and opponents tend to acknowledge. Here's a decent summary from the YouTube Crash Course series on economics: