The Democrats picked up open seats in Kentucky and South Dakota, and defeated four incumbent senators: Gordon Allott of Colorado, J. Caleb Boggs of Delaware, Jack Miller of Iowa, and Margaret Chase Smith of Maine.

The Republicans picked up open seats in New Mexico, North Carolina, and Oklahoma, and defeated one incumbent, William B. Spong Jr. of Virginia.

These were the first elections in which all citizens at least 18 years of age (instead of 21, and older) could vote, due to the 1971 passage of the 26th Amendment.

John Sparkman, who had served as U.S. Representative since 1937 and was House Majority Whip, secured the endorsements of party leaders and ran unopposed to win the remainder of Bankhead's term.

Sparkman also served as the running mate of Adlai Stevenson II in an unsuccessful 1952 presidential campaign.

However, in 1966, the Democratic Party began to feel the backlash of Civil rights legislation in the South, and Sparkman faced his closest political contest to date.

Stevens won re-election in a landslide even as Democrat Mike Gravel served as the state's other senator.

Boggs, a longtime Delaware political figure, was considering retirement which would likely have led to a primary campaign between two Republicans, U.S. Representative Pete du Pont and Wilmington Mayor Harry G. Haskell Jr. To avoid the anticipated divisive primary fight, U.S. President Richard M. Nixon helped convince Boggs to run again with full party support.

[6] Biden's campaign issues focused on withdrawal from Vietnam, the environment, civil rights, mass transit, more equitable taxation, health care, the public's dissatisfaction with politics-as-usual, and "change".

Russell supported segregation in the South and opposed Civil Rights legislation as was common among Southern Democrats of the time.

In the special election to fill the remainder of Russell's term, Nunn faced Republican congressman Fletcher Thompson.

Nunn had support from numerous prominent Georgia Democrats, including Gambrell and Carter.

Though Thompson performed well in the Atlanta metro area, Nunn swept most rural counties en route to a victory.

[12] Nunn also proved to be more moderate than his predecessor Russell, voting in favor of abortion rights, gun control, affirmative action, and environmental regulations.

Percy was opposed by: Democratic nominee Roman Pucinski, a Congressman from Illinois's 11th congressional district, Edward C. Gross (SL) and Arnold Becchetti (C).

In the midst of his campaign for a seventh term, Allen J. Ellender, the President Pro Tempore and chairman of the Appropriations Committee, suffered a fatal heart attack on July 27, 23 days prior to the Democratic primary.

On the same day as Edwards' inauguration on Capitol Hill, the Louisiana Democratic Party rejected a challenge by former Governor John McKeithen to reopen qualifying following Ellender's death, ordering the primary to be held August 19 as scheduled, ignoring an opinion to the contrary by Louisiana Attorney General William J. Guste Jr. Ellender's name was not removed from the ballot and he received 10 percent of the primary vote as a tribute.

McKeithen, whose eight-year gubernatorial tenure ended May 9, 1972, ran as an independent with support of the Ellender family, incensed by Johnston's primary challenge.

Johnston easily won the Democratic primary, nullifying the need for a September 30 runoff.

In the general election, the Shreveport native trounced McKeithen by 32 points to win the first of his four terms.

After winning the Democratic primary, he moved on to the general election, where he faced Hank Hibbard, a State senator and the Republican nominee.

Following a close campaign, Metcalf managed to narrowly win re-election to his third term in the Senate over Hibbard.

Bernie Sanders, the Liberty Union candidate,[26] was later elected to this seat in 2006, serving as an Independent.