WASHINGTON — Moments after making remarks in Jerusalem about Middle East culture that enraged Palestinians and undermined the public relations value of his trip to Israel, Mitt Romney looked around the room for Dan Senor, one of his campaign’s top foreign policy advisers.

It was Mr. Senor’s book about entrepreneurs in Israel that informed his comments, Mr. Romney explained to the group of Jewish-American donors he had assembled at the King David hotel. The book, “Start-up Nation,” is among Mr. Senor’s writings that Mr. Romney frequently cites in public.

Mr. Senor (pronounced See-NOR) has become one of the key people shaping Mr. Romney’s increasingly hawkish views on the Middle East. A television-savvy former spokesman for the American government in Iraq, Mr. Senor blends a foreign policy background, high-volume punditry and ties to wealthy hedge fund investors in the United States to become a triple threat as an insider in Mr. Romney’s presidential campaign.

His presence in the tight orbit of advisers around the Republican candidate foreshadows a Romney foreign policy that could take a harder line against Iran, embrace Jerusalem as the capital of Israel and move away from being the honest broker in the conflict with Palestinians.