Congressional approval was required for any design change within 25 years of the last. In early December, Representative Henry Gonzalez (Democrat-Texas) introduced a bill for Kennedy to appear on the half dollar. On December 10, the new President, Lyndon Johnson, endorsed the call for a Kennedy half dollar, asking Congress to pass the legislation promptly to allow striking of the new piece to begin early in 1964. President Johnson stated that he had been moved by letters from many members of the public to agree with the plan. The bill to authorize the Kennedy half dollar passed on December 30, 1963. Work was already underway on coinage dies; the use of the already-available designs allowed for the completion of the first dies on January 2, 1964. Only proof coins were initially struck. The first Kennedy half dollars intended for circulation were struck at the Denver Mint on January 30, 1964, followed by the Philadelphia Mint the next week. A ceremonial first strike was held at both Philadelphia and Denver on February 11, 1964.