Cushing was created Cardinal-Priest of Santa Susanna by the decision of Pope John XXIII in the consistory of December 15, 1958. He was one of the cardinal electors in the 1963 papal conclave, which elected Pope Paul VI. A close friend of the Kennedy family, he officiated at the marriage of John F. Kennedy and Jacqueline Lee Bouvier in 1953, at which he also read a special prayer from Pope Pius XII, and baptized many of the Kennedy children. Cushing gave the prayer invocation at Kennedy's inauguration in 1961. The Cardinal also celebrated President Kennedy's funeral Mass in 1963 at St. Matthew's Cathedral, Washington, D.C., following Kennedy's assassination in Dallas, Texas. The day before the funeral, he gave a televised eulogy for the President. Cushing later defended Jacqueline Kennedy after her marriage to Aristotle Onassis in 1968. He received a large amount of hate mail and was contradicted by the Vatican.