His grandfather, Joseph Medill, was the founder and owner of the Chicago Tribune. In 1911, he became the president of the company that produced the newspaper.
During the First World War Robert McCormick joined the U.S. Army. In June 1918 he reached the rank of colonel in the field artillery. He served in the 1st Battery, 5th Field Artillery Regiment, with the 1st Infantry Division.
McCormick developed extreme right-wing opinions and during the 1930s he was a strong opponent of President Franklin D. Roosevelt and his New Deal. He was also a founder member of theAmerica First Committee (AFC) that was established in September 1940. Other members of the AFC included Robert E. Wood, John T. Flynn, Charles A. Lindbergh, Burton K. Wheeler, Hugh Johnson, Robert LaFollette Jr., Amos Pinchot, Hamilton Fish and Gerald Nye.
The America First Committee soon became the most powerful isolationist group in the United States. The AFC had four main principles: (1) The United States must build an impregnable defense for America; (2) No foreign power, nor group of powers, can successfully attack a prepared America; (3) American democracy can be preserved only by keeping out of the European War; (4) "Aid short of war" weakens national defense at home and threatens to involve America in war abroad.
In April 1941, Father Charles Coughlin endorsed the America First Committee in his journal, Social Justice. Although Coughlin was one of America's most popular political figures at the time, his open Anti-Semitism made his endorsement a mixed blessing.
Supporters of the America First Committee in the Senate attempted to defeat the administration's Lend Lease proposal. Gerald Nye, Burton K. Wheeler, Hugh Johnson, Robert LaFollette Jr., Henrik Shipstead, Homer T. Bone, James B. Clark, William Langer, and Arthur Capper, all voted against the measure but it was passed by 60 votes to 31.
In a speech in Des Moines, Iowa, Charles A. Lindbergh claimed that the "three most important groups who have been pressing this country toward war are the British, the Jewish and the Roosevelt administration". Soon afterwards Gerald Nye argued "that the Jewish people are a large factor in our movement toward war." These speeches resulted in some people claiming that the America First Committee was anti-Semitic.
The America First Committee influenced public opinion through publications and speeches and within a year the organization had 450 local chapters and over 800,000 members. The AFC was dissolved four days after the Japanese Air Force attacked Pearl Harbor on 7th December, 1941.
In 1955 Robert McCormick joined forces with Robert Wood, chairman and president of Sears, Roebuck & Company to establish American Security Council (ASC). Wood and McCormick started the ASC because they believed that the United States had lost the Korean War because of communist infiltrators. Early members included Douglas MacArthur, Sam Rayburn, Ray S. Cline, Thomas J. Dodd, W. Averell Harriman, Nelson A. Rockefeller, Eugene V. Rostow, John G. Tower, John K. Singlaub, Lawrence P. McDonald and Patrick J. Frawley.
The ASC was behind the establishment of the Mid-America Research Library (MARL). The objective of this organization was to compile files on suspected communists who might apply for jobs in the private sector. This blacklist, that included 6 million names, was provided to 3,500 companies. ASC/MARL worked very closely with the FBI and the House UnAmerican Activities Committee.
Robert Rutherford McCormick died on 1st April, 1955.