In foreign affairs, Johnson's presidency was dominated by the Cold War and the Vietnam War. He pursued conciliatory policies with the Soviet Union, setting the stage for the détente of the 1970s. He was nonetheless committed to a policy of containment, and he escalated the U.S. presence in Vietnam in order to stop the spread of Communism in Southeast Asia during the Cold War. At the same time, the New Deal coalition that had unified the Democratic Party dissolved, and Johnson's support base eroded with it. Influenced by the Keynesian school of economics, Kennedy had proposed a tax cut designed to stimulate consumer demand and lower unemployment. Kennedy's bill was passed by the House, but faced opposition from Harry Byrd, the chairman of the Senate Finance Committee.