1980 United States Senate elections

The 1980 United States Senate elections were held on November 4, coinciding with Ronald Reagan's victory in the presidential election. The 34 Senate seats of Class 3 were contested in regular elections. Reagan's large margin of victory over incumbent Jimmy Carter gave a huge boost to Republican Senate candidates, allowing them to flip 12 Democratic seats and win control of the chamber for the first time since the end of the 83rd Congress in January 1955. This was the first time since 1966 that any party successfully defended all their own seats.

This is one of only five occasions where ten or more Senate seats changed hands in an election, with the others being in 1920, 1932, 1946, and 1958. This is the earliest Senate election with a senator that is still serving, that being Chuck Grassley of Iowa.

This was the largest Senate swing since 1958 and the largest Republican gain since 1946, when the Republicans also picked up 12 seats. This was also the last time the Senate changed hands in a presidential election year until 2020 when Democrats won control, the last time the Republicans gained control of the Senate in a presidential election year until 2024, and the last time Maryland elected a Republican to the Senate.

Results summary

{| style="width:50em; text-align:center"

|+ ↓

|- style="color:white"

| style="background:; width:46%" | 46

| style="background:; width:1%" | 1

| style="background:; width:53%" | 53

| Democratic

| I

| Republican

{| class=wikitable style=text-align:center

|- valign=bottom

! rowspan=2 colspan=2 | Parties

| style="background-color:" |

! rowspan=2 | Total

|- valign=bottom

! Democratic

! Republican

! Independent

! Libertarian

! Other

! colspan=2 | Last elections (1978) Before these elections

| | 58

| 41

| 1

| 0

! 100

! colspan=2 style="background:#bbb" | Not up

| | 34

| 31

| 1

| 0

! 66

| colspan=100 |

! colspan=2 style="background:#bbb" | Up

| | 24

| 10

| 0

| —

! 34

| colspan=100 |

! colspan=2 style="background:#ccc" | Incumbent retired

| 2

| | 3

| —

! 5

! rowspan=3 |

| 2

| | 3

| —

! 5

| 0

| —

! 0

! Result

! 2

! | 3

! —

! 5

! colspan=2 style="background:#ccc" | Incumbent ran

| | 22

| 7

| —

! 29

! rowspan=5 |

| | 10

| 6

| —

! 16

| colspan=2 | 9 Democrats replaced by 9 Republicans

| —

! 9

| 0

| | 1

| —

! 1

| colspan=2 | 3 Democrats replaced by 3 Republicans

| —

! 3

! Result

! 10

! | 19

! 0

! —

! 29

| colspan=100 |

! colspan=2 | Total elected

! 12

! | 22

! 0

! 34

! colspan=2 | Net gain/loss

| 12

| | 12

! 12

! colspan=2 style="background:#ccc" | Nationwide vote

| | 30,699,463

| 26,597,169

Alaska

Incumbent Democrat Mike Gravel ran for a third term, but lost in the Democratic primary to Clark Gruening, a former state representative who was the grandson of Ernest Gruening, whom Gravel had defeated twelve years prior in an election for the same seat. Gruening later went on to lose the general election to Republican nominee Frank Murkowski, a banker.

After the loss of Gravel's seat, no Alaska Democrat would win a congressional race again until Mark Begich's narrow, protracted triumph in Alaska's 2008 Senate election.

First elected in 1968, by 1980 two-term Democratic incumbent Mike Gravel had become noted for a filibuster that attempted to end the draft during the Vietnam War and for including the full text of the Pentagon Papers in the Congressional Record.

Gravel faced a challenging bid for re-election, complicated by the fact that his triumph over Ernest Gruening years prior had made him a pariah in the Alaska Democratic Party. Though Gravel had campaigned to be selected as George McGovern's running mate in the 1972 U.S. presidential election and had easily won re-election to the Senate in 1974, he had never established a strong political base in Alaska.

The passage of a controversial land bill earlier in the year, as opposed to a compromise bill worked out by fellow senator Ted Stevens that failed thanks to Gravel two years prior, further harmed his re-election bid. A group of Democrats, including future governor Steve Cowper, campaigned against Gravel on the land bill issue.

The sources of Gravel's campaign funds, some of which came from political action committees outside the state, also became an issue in the contest.

Arkansas

Incumbent Democrat Dale Bumpers won re-election to a second term over real estate broker William Clark.

California

Incumbent Democrat Alan Cranston easily won re-election to a third term over Paul Gann, political activist, even as the state's former Republican governor, Ronald Reagan, claimed a landslide victory in the presidential election.

Colorado

Incumbent Democrat Gary Hart won re-election to a second term over Mary Estill Buchanan, Colorado Secretary of State.

Florida

Incumbent Democrat Richard Stone decided to run for re-election to a second term, but was defeated in the Democratic primary election by Bill Gunter. Republican Paula Hawkins won the open seat. Six Democrats entered the race for Stone's seat including his 1974 runoff opponent Bill Gunter who was Florida State Treasurer/Insurance Commissioner in 1980.

Hawaii

Incumbent Democrat Daniel Inouye was re-elected to a fourth term, defeating Republican Cooper Brown.

Indiana

Incumbent Democrat Birch Bayh ran for a fourth term, but was defeated by Republican Dan Quayle.

Birch Bayh, the incumbent senator, faced no opposition within the Indiana Democratic Party and avoided a primary election. Bayh was originally elected in 1962 and re-elected in 1968 and 1974. He was Chairman of Senate Intelligence Committee and architect of 25th and 26th Amendments. This election was one of the key races in the country, and signaled a trend that would come to be known as Reagan's coattails, describing the influence Ronald Reagan had in congressional elections. Incumbent three-term senator Birch Bayh was defeated by over 160,000 votes to Representative Dan Quayle, who would later go on to be Vice President of the United States.

| colspan=4 | Republican gain from Democratic

Iowa

Incumbent Democrat John Culver sought re-election to a second term in the Senate, but he was unsuccessful in his bid to do so, falling to Chuck Grassley, the United States Congressman from Iowa's 3rd congressional district, the Republican nominee.

Louisiana

Incumbent Russell B. Long ran for re-election to a seventh and final term, defeating State Representative Woody Jenkins.