In the 1980s Modern Orthodox Rabbi Norman Lamm, Rosh Yeshiva of Yeshiva University, along with other American and Israeli Orthodox rabbis, worked with Conservative and Reform rabbis to come up with solution to the "Who is a Jew?" issue. In 1989 and 1990 Israeli Prime Minister Yitzhak Shamir spearheaded an effort to find a way to resolve the impasse.[citation needed]