John A. McWhorter, 56, a partner in the Washington law firm of King & King and a specialist in the public contract field, died of a heart attack April 19 while on a business trip in the Republic of Panama.

Mr. McWhorter, who lived in Washington, was born in Greensboro, Ga. He earned undergraduate and law degrees at Washington & Lee University. He moved to Washington in 1950 as a lawyer for the Army, working for the Corps of Engineers and in Europe. He joined King & King in 1955. A year later, he earned a master's degree at George Washington University law school.

Mr. McWhorter was active in the American Bar Association and helped draft its Model Procurement Code, which has been adopted by many state and local governments. He was a former chairman of the ABA's public contracts section. He also was a member of the Legal Remedy Study Group of the Commission on Government Procurement. He had been chairman of the Court of Claims Committee of the Bar Association of the District of Columbia.

Survivors include a brother, Sanders McWhorter of Whiteville, N.C., and two sisters, Ann Palmer of Falls Church, and Winifred Nunn of Warrenton, N.C.