William Broderick Prendergast, 85, a former political science professor, researcher, writer and consultant, died of a heart attack Dec. 7 at Arlington Hospital. He lived in McLean.

Dr. Prendergast was research director for the Republican National Committee from 1957 to 1968 and for the Republican Conference in 1969, and he helped write national party platforms in the 1960s. In the early 1970s, he was special assistant to the U.S. defense secretary and was defense adviser to the U.S. mission to NATO. He worked for the ACTION program of the Office of Economic Opportunity until 1976.

After he left government, Dr. Prendergast lobbied for organizations that included the Distilled Spirits Council.

He was a native of Bridgeport, Conn. He graduated from the University of Notre Dame, where he also received a master's degree in political science. He studied at the University of Louvain in Belgium and received a doctorate in political science from the University of Chicago.

During World War II, he was posted by the Army to the Office of Strategic Services.

Dr. Prendergast taught history and political science at the U.S. Naval Academy from 1946 to 1956 and also taught courses in government and international relations at Johns Hopkins and Catholic universities.

He wrote for organizations that included the American Enterprise Institute and for the American Political Science Review and other publications. His book "The Catholic Voter in American Politics" was published in June.

He was a member of St. John's Catholic Church in McLean, the Capitol Hill Club, the Notre Dame Club of Washington, the American Political Science Association, the American Catholic Historical Association, the Catholic Historical Society of Washington, the Brent Society and the Eisenhower World Affairs Institute.

Survivors include his wife of 57 years, Mary Prendergast of McLean; three children, William Prendergast Jr. of McLean, Michael Prendergast of Pittsburgh and Martha Shiles of Bowie; and 11 grandchildren. A son, Richard Prendergast, died in 1990.