From his article 1974 Midterms Bolster Liberalism in Congress:
Perhaps the most important effects of the midterm elections came in foreign policy, however. The new Congress was much more willing to confront the President—and much less willing to confront the spread of communism. When North Vietnam violated the 1973 cease-fire agreement and invaded the South again in 1975, Ford desperately asked Congress for funds to re-supply the South before it was overrun. Congress refused, and on April 30, 1975, Saigon fell. In a certain respect, the midterm elections of 1974 sealed the fate of Indochina.Busch Midterm Election Series:
When Portugal gave up control of Angola and Mozambique in 1975, the Soviets and Cubans began aiding the pro-communist MPLA guerrilla group. When Ford asked Congress to help fund the pro-western group UNITA, it not only refused but passed the Clark amendment permanently enjoining any sort of aid to UNITA. (The Clark amendment was finally repealed in 1985.)
In both houses, liberal Democrats were emboldened to hold public hearings about CIA covert operations. Those hearings not only embarrassed the executive branch but arguably conveyed information that was damaging to national security. The hearings resulted in intelligence "reforms" that hamstrung intelligence and covert operations for the rest of the decade.
Altogether, the Congress elected in 1974 set about almost immediately to undermine the capacity of the United States and its friends to resist the expansion of Soviet power in the world. The record of that Congress might profitably be considered by Americans before they vote in November 2006. Congressional elections might typically hinge on issues like the economy and scandal, but the consequences of those elections can reach far afield, and sometimes can even make vain the sacrifices of many.
1978 GOP Sets Stage for Reagan
1974 Midterms Bolster Liberalism in Congress
1966 Midterm Foreshadows Republican Era
1958-1962 Midterms Pave Way for Great Society
1946 Midterm Gives GOP First Majority Since 1928 Elections, Helps Ensure Truman’s Reelection
The New Deal Comes to a Screeching Halt in 1938
1930 Midterms Heralded New Deal