Actually, of the 248 vetos in the history of the Security Council, 73 have been used by the US, 29 with regard to the Middle East.(1)
There are many impartial countries, the most competent and experienced being the European countries. The EU should take over America's role, since they don't give Israel some $8 billion a year in aid (much is hidden as loans or forgiven debts, free military hardware and the like). The EU, despite its frequent condemnation of Israel, trades favourably with Israel and allows them to participate in European sporting events despite not being European. Note their is a difference between being impartial and not having a postion. Impartial does not mean treating both sides as if they are equally to blame, it means assigning blame based on clear-headed examination of the facts. And what does the Arab/Jewish minorities have to do with it? If anything this is a reason the US should relinquish its mediator status, since the Jewish lobby is so powerful in America, and lobbying is considered an enemy of democracy in Europe.
1. http://www.unol.org/messages/41212.shtml