In 1948, in response to moves by the Western powers to establish a separate, federal system of government in the Western zones, and to extend the Marshall Plan to Germany, the Soviets instituted the Berlin Blockade, preventing people, food, materials and supplies from arriving in West Berlin by land routes through the Soviet zone. The United States, the United Kingdom, France, Canada, Australia, New Zealand and several other countries began a massive "airlift", supplying West Berlin with food and other supplies. The Soviets mounted a public relations campaign against the Western policy change. Communists attempted to disrupt the elections of 1948, preceding large losses therein, while 300,000 Berliners demonstrated for the international airlift to continue. In May 1949, Stalin lifted the blockade, permitting the resumption of Western shipments to Berlin.