McCormack served as a member of United States House of Representatives from 1928 until he retired from political life in 1971. A Democrat, McCormack served as House Majority Leader three times, the first time from 1940 to 1947, the second time from 1949 to 1953, and again from 1955 to 1961. He served as Speaker of the House of Representatives from 1962 until 1971.
McCormack was born to Joseph H. McCormack, a hod carrier, and Ellen (née O'Brien) McCormack. His parents were both the children of Irish immigrants who had arrived during the Irish potato famine in 1848. There were 12 children, of whom three survived to adulthood. McCormack was 13 when his father died; he quit school after the eighth grade to help support his widowed mother and family as a $3-a-week errand boy for a brokerage firm. His career began when he shifted to a law firm for a 50-cent raise and studied law on the side. Attending law school at night, he passed the Massachusetts bar exam in 1913 at age 21 without having completed high school.
He served in the United States Army in World War I in 1917 and 1918. Making a name as a Boston trial lawyer, he moved up the ranks in the state legislature (serving in the House from 1920 to 1922 and in the Senate from 1923 to 1926), and was elected to the United States Congress in 1928 to fill the vacancy caused by the death of James A. Gallivan.
He moved up fast in the House, thanks to Speaker John Nance Garner, who put him on the powerful Ways and Means Committee in his second term. A New Deal supporter, he maintained an unwaveringly liberal voting record to the end. In 1934 he served as chair of the House Un-American Activities Committee. The main goal of HUAC at that time was investigating Nazi propaganda. He was a staunch anti-Communist crusader as well. He played a key role in extending the military draft just before the Attack on Pearl Harbor at a time when isolationism still ran high.
In 1936 McCormack backed Sam Rayburn's bid to become Speaker; when the latter did so in 1940, he chose McCormack as Floor Leader (Majority and Minority Leader, depending on who controlled a particular Congress), serving until Rayburn died in 1961. He was quite belligerent in this role, usually on the floor during a session, slumped in a front row seat holding a dead cigar, ready to leap into debate with a partisan bite. During the 1950s, his method of urging bi-partisan support was to yell across at Republicans that President Dwight D. Eisenhower would never have got anything done without Democratic help. He usually irritated someone.
McCormack's nine years as Speaker saw landmark legislation in the fields of civil rights (for which he fought early on), education, health care for the elderly and welfare – it was he who presided over the Great Society Congress. However, the latter part of his tenure saw increasing focus on the Vietnam War, which he supported. His manner changed during these years: he was impeccably fair and impartial, never ignoring an obstreperous member seeking recognition to make a troublesome point of order. His rare floor speeches usually were restrained. His demeanor generally was that of a kindly elder relative with an unruly brood. According to one member, his strength was his personal consideration of members, which inspired in return affection and a desire to help; his weakness, that he couldn't control the powerful committee chairmen who wield great power in the House. A tall, thin, silver-haired, teetotaling Irishman who liked to wheel and deal with an arm around the shoulder, he maintained warm ties with some Southerners whom Rayburn could never budge, but never quite mastered Rayburn's talent for making the House behave.
McCormack could properly claim that he was a "national" congressman. He fought for farm bills, even though he said he hadn't "more than five flower pots in my whole district." On a close vote on a cotton bill, the Speaker could be found sweeping members from the lobbies onto the floor, the job of an assistant whip.
At times he was beset by problems. The House met all year in 1963 without finishing its work, and wound up sitting through one futile all-night session, finally passing the last bill at a 7 a.m. session. The House Appropriations Committee conducted an unseemly squabble with the Senate all through 1962 over where to meet, and Appropriations Committee Chairman Clarence Cannon closed the session with a speech blasting the House leadership as the worst he had seen in 40 years.
Between the assassination of John F. Kennedy on November 22, 1963 and the swearing-in of Hubert Humphrey as Vice President on January 20, 1965, McCormack was the first person in the line of succession for the Presidency, and he received Secret Service protection. When Kennedy died in 1963, McCormack recalled his experiences serving as next-in-line in an article he wrote for The Boston Globe.
In January 1969, Arizonan Morris Udall attempted to unseat and replace McCormack. In 1970, the sniping by young liberals at McCormack increased and several congressmen urged him to step down because he was too old. One Congressman, Jerome R. Waldie of California, asked a party caucus to declare a lack of confidence in his leadership; it did not. McCormack kept his decision to leave the House a secret from his closest friends there until he announced it publicly in May 1970.
In 1983, the University of Massachusetts Boston established the John W. McCormack Institute of Public Affairs, named in McCormack's honor. In 2003 it was expanded into the John W. McCormack Graduate School of Policy Studies.
In 1920, McCormack married Harriet Joyce, a former singer; the couple had no children. While Congress was in session, they lived at the Washington Hotel. Their devotion to each other was legendary; it was said that they never spent a night apart until she died. If the Speaker was kept late on business, his wife always went up to have dinner with him. She died in December 1971, aged 87. For more than a year, he had spent every night in an adjoining hospital room. He then went home to Boston the following month, after his retirement.
McCormack had few hobbies except politics. In earlier days, he was known as a good high stakes poker player. He never flew in an airplane until 1961, when he attended Rayburn's funeral. He drove the 450 miles from Washington to Boston or went up on the night sleeper train.
The Speaker and his wife were devout Roman Catholics. Both were honored by the Vatican. He was the first Catholic to be elected Speaker, and some critics complained that this religion sometimes showed in his leadership qualities. An example cited was the 1961 school aid debacle when McCormack insisted that church schools should share in a federal aid program. The bill died on this issue. But in 1963 McCormack helped push through the largest education program in history, much of which went to public institutions only.
At home in his district, he could usually be found visiting sick rooms or political clubs. His personal kindnesses were legion, and if he harbored vindictiveness it was hard to see. Pundits predicted foot-dragging by the Speaker after President Kennedy's 30-year-old brother Ted won a Senate seat from McCormack's favorite nephew, the highest Democratic officeholder in the state and a logical candidate. McCormack never showed by word or deed that he bore a grudge.