Arthur Hendrick Vandenberg Sr. (March 22, 1884 April 18, 1951) was an American politician who served as a United States senator from Michigan from 1928 to 1951. A member of the Republican Party, he participated in the creation of the United Nations. He is best known for leading the Republican Party from a foreign policy of isolationism to one of internationalism, and supporting the Cold War, the Truman Doctrine, the Marshall Plan, and NATO. He served as president pro tempore of the United States Senate from 1947 to 1949.
Born and raised in Grand Rapids, Michigan, in a family of Dutch Americans, Vandenberg began his career as a newspaper editor and publisher. In 1928, Republican Governor Fred W. Green appointed Vandenberg to the U.S. Senate to fill the vacancy that arose after the death of Woodbridge N. Ferris. Vandenberg won election to a full term later that year and remained in the Senate until his death in 1951. He supported the early New Deal programs but came to oppose most of President Franklin D. Roosevelt's domestic policies. During the late 1930s, Vandenberg also opposed the United States' becoming involved in World War II and urged Roosevelt to reach an accommodation with Japan.
Vandenberg abandoned his isolationism after the Japanese attack on Pearl Harbor. He became chairman of the Senate Foreign Relations Committee in 1947 and supported Democratic President Harry Truman's Cold War policies, asserting that "politics stops at the water's edge." Vandenberg also served as the chairman of the Republican Senate Conference from 1945 to 1947 and as the president pro tempore of the Senate from 1947 to 1949. He unsuccessfully sought the Republican nomination for president in 1940 and 1948.
Vandenberg was born and raised in Grand Rapids, Michigan, the son of Alpha (née Hendrick) and Aaron Vandenberg, of mostly Dutch heritage. Vandenberg attended the public schools of Grand Rapids and graduated from Grand Rapids Central High School in June 1900 ranked first in his class.