Speaking on Saturday at the World Economic Forum being held in Jordan, Senator Gordon Smith said Washington's priority was to secure Israel in a way that, if possible, was just to the Palestinians.
He advised Arab leaders to worry more about injustices in their own countries.
"It's a mystery to me why Arab countries can't work on their own countries before Palestine is fixed," Smith said in a discussion at the forum.
Smith, a Republican from Oregon, said the peace process, aimed at bringing about an independent Palestinian state, was unlikely to win a serious commitment from the Bush administration.
"Until we have someone on the other side, who is willing to say, "Yes, we're not going to continue to prostitute the American presidency to people who aren't serious," Smith bluntly told a prestigious panel that included Arab League Secretary-General Amr Moussa and top officials from Jordan, the Palestinian territories, Iraq and Afghanistan, as well as academics from Iran and Turkey.
Asked why the United States was willing to anger Arab countries in favour of Israel, another Congressman, Republican Christopher Shays, said simply that America was not a neutral player in the Middle East.
"We are Israel's strong ally," Shays, Republican of Connecticut, said in an interview with The Associated Press.
"It would be foolish for people to think that somehow we are neutral," he added.