Commissioner Pete Rozelle also became chief executive of the AFL from July 26, 1966, through the completion of the merger. During this time the AFL expanded, adding the Miami Dolphins and Cincinnati Bengals. After losses by the Kansas City Chiefs and Oakland Raiders in the first two AFL-NFL World Championship Games to the Green Bay Packers (1966–67), the New York Jets and Chiefs won Super Bowls III and IV (1968–69) respectively, cementing the league's claim to being an equal to the NFL. In 1970, the AFL was absorbed into the NFL and the league reorganized with the ten AFL franchises along with three existing NFL teams: the Baltimore Colts, the Cleveland Browns, and the Pittsburgh Steelers, becoming part of the newly formed American Football Conference. League history During the 1950s, the National Football League had grown to rival Major League Baseball as one of the most popular professional sports leagues in the United States. One franchise that did not share in this newfound success of the league was the Chicago Cardinals – owned by the Bidwill family – who had become overshadowed by the more popular Chicago Bears. The Bidwills hoped to move their franchise, preferably to St. Louis, but could not come to terms with the league, which demanded money before it would approve the move. Needing cash, the Bidwills began entertaining offers from would-be investors, and one of the men who approached the Bidwills was Lamar Hunt, son and heir of millionaire oilman H. L. Hunt. Hunt offered to buy the Cardinals and move them to Dallas, where he had grown up. However, these negotiations came to nothing, since the Bidwills insisted on retaining a controlling interest in the franchise and were unwilling to move their team to a city where a previous NFL franchise had failed in . While Hunt negotiated with the Bidwills, similar offers were made by Bud Adams, Bob Howsam, and Max Winter. When Hunt, Adams, and Howsam were unable to secure a controlling interest in the Cardinals, they approached NFL commissioner Bert Bell and proposed the addition of expansion teams. Bell, wary of expanding the 12-team league and risking its newfound success, rejected the offer. On his return flight to Dallas, Hunt conceived the idea of an entirely new league and decided to contact the others who had shown interest in purchasing the Cardinals. In addition to Adams, Howsam, and Winter, Hunt reached