2004 United States Senate elections

The 2004 United States Senate elections were held on November 2, 2004, with all Class 3 Senate seats being contested. They coincided with the re-election of George W. Bush as president and the United States House elections, as well as many state and local elections. Senators who were elected in 1998, known as Senate Class 3, were seeking re-election or retiring in 2004.

Republicans won six seats but lost two themselves, giving them a net gain of four seats. Five of the six gains came from states in the region of the Southern United States. Democrats Fritz Hollings of South Carolina, John Breaux of Louisiana, Bob Graham of Florida, and Zell Miller of Georgia chose to retire, while John Edwards of North Carolina chose to run for the Democratic nomination for president, and was subsequently selected as the Democratic nominee for vice president. They were succeeded by Republicans Jim DeMint, David Vitter, Mel Martinez, Johnny Isakson, and Richard Burr, respectively.

In South Dakota, Republican John Thune defeated the incumbent Senate minority leader Tom Daschle, marking the first and only time since 1952 that a sitting party leader lost re-election, as well as the only time that person was the minority leader. Republican senator Peter Fitzgerald of Illinois chose not to run for re-election, and Democrat (and future president) Barack Obama won in a landslide, becoming the Senate's only Black member and only the third popularly elected in American history and only the third elected since Reconstruction. Republican Senator Ben Nighthorse Campbell of Colorado chose not to run for re-election, and Democrat Ken Salazar won the open seat.

This was the third consecutive election cycle for Senate Class 3 in which the Democrats either broke even or lost seats. This also marked the first time since 1980 in which a presidential candidate from either party won with coattails in the Senate. Additionally, these election results are tied with those of 1996 and 1998 as the highest number of Senate seats that the Republicans have held since 1920. In contrast, when accounting for their gains in 2002, it was the last time that the Republicans made net gains in two election cycles in a row as of 2026. Republicans would not make a net gain of seats during a presidential election year again until 2024. This is the last time both major parties were on the general election ballot in every race. As of , this is the most recent election cycle after which the Republican Party ended up with at least 55 Senate seats.

Results summary + ↓ 44 1 55 Democratic Independent Republican Summary of the 2004 United States Senate elections results {| class=wikitable style=text-align:center |- ! colspan=2 rowspan=2 | Parties | style="background-color:" | | style="background-color:" | | style="background-color:" | | style="background-color:" | | style="background-color:" | ! rowspan=2 | Total |- ! Democratic ! Republican ! Independent ! Libertarian ! Others |- ! colspan=2 | Before these elections | 48 | | 51 | 1 | — | — ! 100 |- ! colspan=2 | End of this Congress (two months later) | 48 | | 51 | 1 | — | — ! 100 |- ! colspan=2 | Not Up | 29 | | 36 | 1 | — | — ! 66 |- ! colspan=2 | Up | | 19 | 15 | — | — | — ! 34

| colspan=99 | |- ! rowspan=4 style="background:#ccc" | Incumbentretired ! Total before | | 5 | 3 | — | — | — ! 8 |- ! Held by same party | — | | 1 | — | — | — ! 1 |- ! Replaced by other party | colspan="2" | 2 Republicans replaced by 2 Democrats 5 Democrats replaced by 5 Republicans | — | — | — ! 7 |- ! Result after | 2 | | 6 | — | — | — ! 8 |- ! rowspan=6 style="background:#cccccc" | Incumbentran ! Total before | | 14 | 12 | — | — | — ! 26 |- ! Won re-election | | 13 | 12 | — | — | — ! 25 |- ! Lost re-election | colspan=2 | 1 Democrat replaced by 1 Republican | — | — | — ! 1 |- ! Lost renomination, held by same party | — | — | — | — | — ! 0 |- ! Lost renomination, and party lost | — | — | — | — | — ! 0 |- ! Result after | 13 | 13 | — | — | — ! 26 |- ! colspan=2 | Net gain/loss | 4 | | 4 | — | — | — ! 4 |- ! colspan=2 | Total elected | 15 | | 19 | — | — | — ! 34

| colspan=99 | |- ! colspan=2 | Result ! 44 ! | 55 ! 1 ! — ! — ! 100

| colspan=99 | |- ! rowspan=2 style="background:#cccccc" | Popularvote ! Votes ! | 44,754,618 | 39,920,562 | 186,231 | 754,861 | 2,481,075 ! 88,097,347 |- ! Share ! | 50.80% | 45.31% | 0.21% | 0.86% | 2.82% ! 100%

Sources: Dave Leip's Atlas of U.S. Elections United States Elections Project at George Mason University

Change in composition

Before the elections D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D I R Majority → R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R

After the elections D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D I R R R R R Majority → R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R

Key: D Democratic I Independent R Republican

Gains and losses Retirements

Three Republicans and five Democrats retired instead of seeking re-election.

StateSenator Age at end of term AssumedofficeReplaced by Colorado 71 1993 Florida 68 1987 Georgia 72 2000 Illinois 44 1999 Louisiana 60 1987 North Carolina 51 1999 Oklahoma 56 1981 South Carolina 83 1966

Defeats Despite several candidates being in danger of losing their re-election bid, South Dakota Democratic senator Tom Daschle was the only incumbent who ran for re-election to be defeated.

StateSenatorAge atend of termAssumedofficeReplaced by South Dakota 57 1987

Post-election changes One Democrat resigned on January 17, 2006, and was replaced by a Democratic appointee.

StateSenatorReplaced by New Jersey(Class 1)

Final pre-election predictions Several sites and individuals publish predictions of competitive seats. These predictions look at factors such as the strength of the incumbent (if the incumbent is running for re-election) and the other candidates, and the state's partisan lean (reflected in part by the state's Cook Partisan Voting Index rating). The predictions assign ratings to each seat, indicating the predicted advantage that a party has in winning that seat.

Most election predictors used: "tossup": no advantage "tilt" (used by some predictors): advantage that is not quite as strong as "lean" "lean": slight advantage "likely" or "favored": significant, but surmountable, advantage "safe" or "solid": near-certain chance of victory

Where a site gives a percentage probability as its primary indicator of expected outcome, the chart below classifies a race as follows: Tossup: 50-55% Tilt: 56-60% Lean: 61-75% Likely: 76-93% Safe: 94-100%

Constituency Incumbent 2004 election ratings State Senator Lastelection Sabato's Crystal Ball Result Alabama 63.24% R Shelby67.55% R Alaska Appointed Murkowski48.58% R Arizona 68.74% R McCain76.74% R Arkansas 55.07% D Lincoln 55.90% D California 53.06% D Boxer 57.71% D Colorado 62.49% R Salazar51.30% D Connecticut 65.15% D Dodd66.35% D Florida 62.47% D Martínez49.43% R Georgia 58.19% D Isakson57.88% R Hawaii 79.18% D Inouye75.51% D Idaho 69.54% R Crapo99.18% R Illinois 50.35% R Obama 69.97% D Indiana 63.72% D Bayh 61.65% D Iowa 68.41% R Grassley70.18% R Kansas 65.27% R Brownback69.16% R Kentucky 49.75% R Bunning 50.66% R Louisiana 64.02% D Vitter51.03% R Maryland 70.50% D Mikulski 64.80% D Missouri 52.68% R Bond56.09% R Nevada 47.86% D Reid61.08% D New Hampshire 67.84% R Gregg 66.24% R New York 54.62% D Schumer71.16% D North Carolina 51.15% D Burr51.60% R North Dakota 63.16% D Dorgan 68.28% D Ohio 56.46% R Voinovich63.85% R Oklahoma 66.38% R Coburn52.77% R Oregon 61.05% D Wyden63.39% D Pennsylvania 61.34% R Specter52.62% R South Carolina 52.70% D DeMint53.67% R South Dakota 62.14% D Thune50.58% R Utah 63.98% R Bennett68.73% R Vermont 72.22% D Leahy70.63% D Washington 58.41% D Murray54.98% D Wisconsin 50.55% D Feingold 55.35% D

Race summary Special elections during the 108th Congress There were no special elections during the 108th Congress.

Elections leading to the next Congress In these general elections, the winners were elected for the term beginning January 3, 2005; ordered by state.

All of the elections involved the Class 3 seats.

State Incumbent Results Candidates Senator Party Electoral history Alabama 198619921998 Incumbent re-elected. Alaska 2002 Interim appointee elected. Arizona 198619921998 Incumbent re-elected. Arkansas 1998 Incumbent re-elected. California 19921998 Incumbent re-elected. Colorado 19921998 Incumbent retired.Democratic gain. Connecticut 1980198619921998 Incumbent re-elected. Florida 198619921998 Incumbent retired.Republican gain. Georgia 2000 2000 Incumbent retired.Republican gain. Hawaii 1962196819741980198619921998 Incumbent re-elected. Idaho 1998 Incumbent re-elected. Illinois 1998 Incumbent retired.Democratic gain. Indiana 1998 Incumbent re-elected. Iowa 1980198619921998 Incumbent re-elected. Kansas 1996 1998 Incumbent re-elected. Kentucky 1998 Incumbent re-elected. Louisiana 198619921998 Incumbent retired.Republican gain. Maryland 198619921998 Incumbent re-elected. Missouri 198619921998 Incumbent re-elected. Nevada 198619921998 Incumbent re-elected. New Hampshire 19921998 Incumbent re-elected. New York 1998 Incumbent re-elected. North Carolina 1998 Incumbent retired to run for Vice President.Republican gain. North Dakota Democratic-NPL 19921998 Incumbent re-elected. Ohio 1998 Incumbent re-elected. Oklahoma 1980198619921998 Incumbent retired.Republican hold. Oregon 1996 1998 Incumbent re-elected. Pennsylvania Republican 1980198619921998 Incumbent re-elected. South Carolina 1966 196819741980198619921998 Incumbent retired.Republican gain. South Dakota 198619921998 Incumbent lost re-election.Republican gain. Utah 19921998 Incumbent re-elected. Vermont 19741980198619921998 Incumbent re-elected. Washington 19921998 Incumbent re-elected. Wisconsin 19921998 Incumbent re-elected.

Closest races

In seven races the margin of victory was under 10%.

District Winner Margin Florida Republican (flip) 1.1% South Dakota Republican (flip) 1.2% Kentucky Republican 1.4% Alaska Republican 3.0% Colorado Democratic (flip) 3.9% North Carolina Republican (flip) 4.6% South Carolina Republican (flip) 9.6%

Alabama

Incumbent Republican Richard Shelby won re-election to a fourth term over Democratic perennial candidate Wayne Sowell.

Shelby, who switched parties ten years prior, had over $11 million cash on hand. Shelby was chairman of the Banking Committee. Wayne Sowell became the first Black U.S. Senate nominee of a major party in Alabama.

Alaska

Incumbent Republican Lisa Murkowski of Anchorage sought election to her first full term after being appointed to serve out the rest of her father, Frank Murkowski, on his unexpired term when he resigned in December 2002 to become governor of Alaska. Her main challenger was Democratic former governor Tony Knowles, her father's predecessor as governor. The younger Murkowski won by a slight margin.

Although Alaska is heavily Republican, popular opinion had swung against the Murkowski family because of a tax increase passed by Governor Frank Murkowski. In addition, multiple voters disapproved of apparent nepotism in the appointment of Lisa Murkowski to the Senate. Knowles, who as mentioned above preceded the elder Murkowski as governor, had enlisted extensive out-of-state support for his bid to take over the younger Murkowski's Senate seat. However, veteran Republican senator Ted Stevens taped advertisements warning Alaskans that electing a Democrat could result in less federal dollars for Alaska.