From 1950-1958, Democrats and Republicans were locked in close combat in Congress. Republicans held a very small majority in both houses from 1953-1955, and Democrats held a very small majority the rest of the time. Even when Democrats had numerical control, liberals did not. A coalition of Republicans and conservative Democrats held sway.

Then the precarious balance was undone. The deep recession of 1957-58, the aging of the Eisenhower administration, and a miscalculation by right-to-work forces who stirred up organized labor with a series of state right-to-work ballot initiatives combined to give Democrats a big win in the 1958 midterm elections. Republicans lost 48 House seats, 13 Senate seats, seven governorships, and 686 state legislative seats. Moreover, almost all of the new Democrats were northern and western liberals. As scholars Edward Carmines and James Stimson argued, new Senate Democrats read "like a who’s who of the Democratic coalition that would dominate the Senate for two decades"—including Edmund Muskie of Maine, Philip Hart of Michigan, Eugene McCarthy of Minnesota, and Thomas Dodd of Connecticut.

Republicans would never come close to regaining control of the Senate until 1980 or the House until 1994. The added Democratic numbers, and the shift toward liberalism among the congressional Democrats, made possible the leftward shift in national policy that took place in the 1960s. Though it was necessary for that shift, it was not sufficient.

Despite bolstered liberalism in Congress, the conservative coalition with the backing of President Eisenhower was able to blunt significant policy movement in the immediate wake of 1958. Democrats were able to put Eisenhower and Republicans on the spot with proposed spending increases, measures like the Forand Bill (forerunner to Medicare), and the like, but they were unable to secure passage.

When John F. Kennedy was narrowly elected in 1960, Democrats actually lost 20 House seats, about 40 percent of their 1958 gain. Most of the New Frontier legislation was bottled up in Congress, and the 1962 midterm elections loomed. Even an average loss by the President’s party would have made progress on his program highly unlikely.

For much of the midterm year, the administration was on the defensive over Cuba. Castro had survived the botched Bay of Pigs invasion and had grown even more truculent. In the late summer, rumors began surfacing that Soviet missiles were being installed on Cuba, but the administration denied it. Some observers thought the GOP might be poised to make big midterm gains at Kennedy’s expense. For his part, the President planned a 19,000-mile speaking campaign, saying "History is so much against us, yet if we can hold our own, if we can win five seats or ten seats, it would change the whole opinion in the House and in the Senate."

When the United States resumed U-2 surveillance over Cuba in October 1962, it became clear that the Soviets were indeed placing nuclear missiles on Cuba, and the missile crisis was on. Kennedy cut his tour short after 5,500 miles, and the campaign was frozen. When the crisis was resolved a few days before balloting, Kennedy was the winner. On Election Day, Democrats won what was widely perceived as a moral victory by fighting Republicans to a draw, losing a mere four seats in the House and actually gaining four seats in the Senate. Democrats also suffered no net loss in governorships, the only time the President’s party could say that from the 1920s to 1986. Some of Kennedy’s fiercest critics, like Senators Walter Judd of Minnesota and Homer Capehart of Indiana, went down to defeat, and so did Richard Nixon in his bid to become Governor of California.

While not as complete as FDR’s 1934 sweep, 1962 was compared by many analysts to that election—a rare midterm win for a presidential party. Intangibly, Democrats received a huge psychological boost, and Kennedy’s claim to an electoral mandate—which in 1960 had seemed slender indeed, if it existed at all—was bolstered.

While Kennedy’s assassination is often credited for the passage of much of his program in 1964, James Sundquist points out that "the ice jam of stalled legislation had been thawing in the months before Dallas," largely due to the President’s new political potency after the 1962 midterms. Even a modest loss of 20 seats, and much more the 30-40 seats some saw possible, would have foreclosed this effect and nearly completed the task, begun two years earlier, of wiping out the Democratic gains of 1958. While Lyndon Johnson benefited greatly from his 1964 landslide and accompanying congressional coattails, his tax cut, the landmark Civil Rights Act, and the structure of the War on Poverty all passed before the 1964 election, with the Congress elected in 1962.

Andrew E. Busch is a Professor of Government at Claremont McKenna College and an Adjunct Fellow of the Ashbrook Center.