2018 United States Senate elections

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35[a] of the 100 seats in theUnited States Senate 51 seats needed for a majority
Majority party Minority party   Leader Mitch McConnell Chuck Schumer Party Republican Democratic Leader since January 3, 2007 January 3, 2017 Leader's seat Kentucky New York Seats before 51 47 Seats after 53 45 Seat change 2 2 Popular vote 34,687,875 52,224,867[b][c] Percentage 38.7% 58.2% Seats up 9 24 Races won 11 22   Third party   Party Independent Seats before 2[d] Seats after 2 Seat change Popular vote 808,370[e] Percentage 0.9% Seats up 2 Races won 2
Results of the elections:      Democratic gain     Republican gain      Democratic hold     Republican hold      Independent hold      No election Rectangular inset (Minn. &Miss.): both seats up for election
Majority Leader before election Mitch McConnell Republican ElectedMajority Leader Mitch McConnell Republican

The2018 United States Senate elections were held on November 6, 2018. Among the 100 seats, the 33 ofClass 1 were contested in regular elections while two others were contested in special elections due to Senate vacancies inMinnesota andMississippi. The regular election winners were elected to six-year terms running from January 3, 2019, to January 3, 2025.SenateDemocrats had 26 seats up for election (including the seats of two Independents whocaucus with them), while SenateRepublicans had nine seats up for election.

To maintain their working majority of 50 senators and their party'svice president's tie-breaking vote, Republicans could only afford a net loss of one seat in these elections. The Republicans had a 52–48 majority after the2016 elections, but they lost a seat in Alabama afterJeff Sessions resigned to becomeU.S. attorney general andDoug Jones, a Democrat, won in thesubsequent special election. Three Republican-held seats were open as a result of retirements inTennessee,Utah, andArizona. Although every Democratic incumbent ran for re-election, Democrats faced an extremely unfavorable map, defending 26 seats, of which 10 were in states won byDonald Trump in the2016 presidential election, in five states by more than 10%. Republicans, meanwhile, only had to defend nine seats, of which only one was in a state won byHillary Clinton in 2016.

The Republicans increased their majority by defeating Democratic incumbents inFlorida,Indiana,Missouri, andNorth Dakota, and holding the open seats in Tennessee and Utah. Democrats captured two Republican-held seats, defeating an incumbent inNevada and winning the open seat in Arizona. This marked the first time that Republicans gained Class 1 Senate seats since 1994. To date, this remains the last time that Democrats won a Senate election in Montana, Ohio, and West Virginia.

The results for this election cycle were the only significant gains made by the Republicans in what was otherwise characterized as a"blue wave" election. The Republican gains in the Senate and the Democratic gains in the House marked the firstmidterm election cycle since1970 in which the president's party made net gains in one chamber of Congress while suffering net losses in the other,^[3] which also occurred in 1914, 1962, and 2022. This was also the first midterm election cycle since2002 in which any incumbents of the non-presidential party lost re-election. The number of defeated non-presidential party incumbents (four) was the most since the 1934 midterms.^[4]

Among the 33Class 1 Senate seats up for regular election in 2018, twenty-three were held by Democrats, two by independents whocaucused with the Senate Democrats and eight by Republicans. Class Two seats inMinnesota andMississippi held by interim appointees were also up for election; both incumbent appointees sought election to finish their unexpired terms.

Democrats targeted Republican-held Senate seats inArizona (open seat) andNevada.^[5] Seats inTexas,^[6]Mississippi (at least one of the two seats) andTennessee (open seat)^[7] were also competitive for the Democrats. Republicans targeted Democratic-held seats inIndiana,Missouri,Montana,North Dakota andWest Virginia, all of which were won by Republicans in both the2012 and2016 presidential elections.^[8] Seats inFlorida,Ohio,Pennsylvania,Wisconsin andMichigan, all of which were won by Obama in 2008 and 2012 but by Trump in 2016, were also targeted by Republicans.^[5][9] The Democratic-held seat inNew Jersey was also considered unexpectedly competitive due to corruption allegations surrounding the Democratic incumbent.

The map was widely characterized as extremely unfavorable to Democrats, as Democrats were defending 26 states while Republicans were defending nine. Of these seats, Democrats were defending ten in states won by Donald Trump in the 2016 presidential election, while Republicans were only defending one seat in a state won by Hillary Clinton in 2016.^[10][11][12] According toFiveThirtyEight, Democrats faced the most unfavorable Senate map in 2018 that any party has ever faced in any election.^[13][14]

Parties									Total
			Democratic	Republican	Independent	Libertarian	Green	Other
Last elections (2016)			46	52	2	0	0	0	100
Before these elections			47	51	2	0	0	0	100
Not up			23	42	0	—	—	—	65
	Class 2 (2014→2020)		11	20	0	—	—	—	31
	Class 3 (2016→2022)		12	22	0	—	—	—	34
Up			24	9	2	—	—	—	35
	Class 1 (2012→2018)		23	8	2	—	—	—	33
	Special: Class 2		1	1	0	—	—	—	2
	Regular elections
	Incumbent retired		0	3	0	—	—	—	3
		Held by same party	—	2	—	—	—	—	2
		Replaced by other party	1 Republican replaced by 1 Democrat						1
		Result	1	2	0	0	0	0	3
	Incumbent ran		23	5	2	—	—	—	30
		Won re-election	19	4	2	—	—	—	25
		Lost re-election	1 Republican replaced by 1 Democrat 4 Democrats replaced by 4 Republicans						5
		Result	20	8	2	0	0	0	30
	Special elections
	Appointee ran		1	1	—	—	—	—	2
		Appointee elected	1	1	—	—	—	—	2
		Result	1	1	0	0	0	0	2
	Total elected		22	11	2	0	0	0	35
	Net gain/loss		2	2					2
	Nationwide vote		52,224,867	34,722,926	808,370	590,051	200,599	1,262,765	90,473,222
		Share	58.17%	38.67%	0.90%	0.66%	0.22%	1.41%	100%
Result			45	53	2	0	0	0	100

Source: Clerk of the U.S. House of Representatives.^[1]

Each block represents one of the one hundred seats in the Senate. "D#" is a Democratic senator, "I#" is an independent senator and "R#" is a Republican senator. Arranged so parties are separated and a majority is clear by crossing the middle.

Each block indicates an incumbent senator's actions going into the election. Some "Ran" for re-election, some "Retired," and those without a note were not up for election this cycle. Before the elections, Republicans held 51 seats, Democrats held 47, and Independents held 2.

After the2017 Senate special election in Alabama on the start of the second session in the 115th Congress.

Some senators were "Re-elected," some were a "Gain" in the seat from the other party (either by beating an incumbent or by winning an open seat), some were a "Hold" by the same party but with a different senator, and those without a note were not up for election this year.

After these elections, Democrats had 45 seats, independents had 2, and Republicans had 53.

Several sites and individuals publish predictions of competitive seats. These predictions look at factors such as the strength of theincumbent (if the incumbent is running for re-election) and the other candidates, and the state's partisan lean (reflected in part by the state'sCook 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

These are the election dates for the regularly scheduled general elections.

Three Republicans retired instead of seeking re-election.

Four Democrats and one Republican sought re-election but lost in the general election.

One Republican resigned before the start of the 116th Congress on December 31, 2018, and another Republican resigned during the 116th Congress for health reasons. Initially, all were replaced by Republican appointees.

In these special elections, the winners will be seated before January 3, 2019, when elected and qualified. They are ordered by election date, then by state and by class.

In these general elections, the winners were elected for the term beginning January 3, 2019.

All of the elections involve the Class 1 seats and they are ordered by state.

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

Arizona election

← 2012 2024 →
Turnout	64.85%
Nominee Kyrsten Sinema Martha McSally Party Democratic Republican Popular vote 1,191,100 1,135,200 Percentage 49.96% 47.61%
Sinema:     50–60%     60–70% McSally:     50–60%     60–70%     70–80%
U.S. senator before election Jeff Flake Republican Elected U.S. senator Kyrsten Sinema Democratic

One-term RepublicanJeff Flake was elected with 49% of the vote in 2012. He chose not to run for re-election.^[30]

U.S. RepresentativeMartha McSally^[31] won the Republican nomination in a three-way primary on August 28, 2018, againstJoe Arpaio andKelli Ward.

U.S. RepresentativeKyrsten Sinema^[31] easily secured the Democratic nomination.

Sinema defeated McSally by a slim margin; her victory became official only after six days of counting ballots.

California election

← 2012 2024 →
Turnout	56.42%
Nominee Dianne Feinstein Kevin de León Party Democratic Democratic Popular vote 6,019,422 5,093,942 Percentage 54.16% 45.84%
County results Feinstein:     50–60%     60–70% de León:     50–60%     60–70%     70–80%
U.S. senator before election Dianne Feinstein Democratic Elected U.S. senator Dianne Feinstein Democratic

Four-term DemocratDianne Feinstein won a special election in 1992 and was elected to full terms in 1994, 2000, 2006, and 2012. She ran for re-election and advanced to the general election after securing the top spot in the June 5 jungle primary.^[33]

The June 5 primary ballot listed 32 candidates (Feinstein plus 31 challengers) in addition to 3write-in candidates. There were 10 Democratic candidates, 11 Republican candidates, one Libertarian, one Peace and Freedom candidate, and 9 independent candidates. There was also a Green Party candidate who ran as a write-in.

President pro tempore of the California State SenateKevin de León advanced to the general election for the right to challenge Feinstein after securing the second spot in the primary.^[33]

The 11 Republican candidates who ran in the primary combined for 33.2% of the vote. The top Republican candidate, James P. Bradley, received 8.3% of the vote, which put him in 3rd place at 3.8% behind the second-place finisher, Kevin DeLeon.^[34]

On November 6,Dianne Feinstein was elected to a fifth term, defeatingKevin de León.

Connecticut election

← 2012 2024 →
Turnout	63.58%
Nominee Chris Murphy Matthew Corey Party Democratic Republican Popular vote 825,579 545,717 Percentage 59.53% 39.35%
County results Municipality results Murphy:     40–50%     50–60%     60–70%     70–80%     80–90%     >90% Corey:     40–50%     50–60%     60–70%
U.S. senator before election Chris Murphy Democratic Elected U.S. senator Chris Murphy Democratic

One-term DemocratChris Murphy was elected with 55% of the vote in 2012. He ran for re-election.^[35]

Businessmen Matthew Corey^[36] received the Republican nomination.

Chris Murphy was elected to a second term, winning nearly 60% of the vote.^[37]

Delaware election

← 2012 2024 →
Turnout	52.18%
Nominee Tom Carper Rob Arlett Party Democratic Republican Popular vote 217,385 137,127 Percentage 59.95% 37.81%
Carper:     50–60%     60–70% Arlett:     50–60%
U.S. senator before election Tom Carper Democratic Elected U.S. senator Tom Carper Democratic

Three-term DemocratTom Carper won re-election with 66% of the vote in 2012. He announced he was running for re-election during an interview onMSNBC on July 24, 2017.^[38] He defeated Dover community activist Kerri Evelyn Harris for the Democratic nomination.Sussex County Councilman Robert Arlett won the Republican nomination.^[38]

Tom Carper defeated Arlett, winning 60% of the vote.^[39]

Florida election

← 2012 2024 →
Turnout	61.68%
Nominee Rick Scott Bill Nelson Party Republican Democratic Popular vote 4,099,505 4,089,472 Percentage 50.05% 49.93%
Scott:     50–60%     60–70%     70–80%     80–90% Nelson:     50–60%     60–70%
U.S. senator before election Bill Nelson Democratic Elected U.S. senator Rick Scott Republican

Three-term DemocratBill Nelson was re-elected with 55% of the vote in 2012. He sought re-election to a fourth term in office.^[40]

Florida GovernorRick Scott won the Republican nomination. First elected in2010 and re-elected in2014, Scott's term asGovernor of Florida was set to end by January 2019, due toterm limits.^[40]

Edward Janowski was running as an independent, but did not qualify.^[40]

Scott led among ballots tallied on election night, but given the close margins of the race recounts were ordered.^[41] Final recount numbers were released following a machine and hand recount with Rick Scott maintaining a lead.^[42] On November 18, Nelson conceded to Scott.^[43] Two days later, election results were certified by the state, cementing Scott's win.^[44]

Hawaii election

← 2012 2024 →
Turnout	51.32%
Nominee Mazie Hirono Ron Curtis Party Democratic Republican Popular vote 276,316 112,035 Percentage 71.15% 28.85%
County results Hirono:     60–70%     70–80%
U.S. senator before election Mazie Hirono Democratic Elected U.S. senator Mazie Hirono Democratic

One-term DemocratMazie Hirono was elected with 63% of the vote in 2012. She ran.^[45]

Ron Curtis was the Republican nominee.

Hirono was elected to a second term by a landslide.

Indiana election

← 2012 2024 →
Turnout	50.42%
Nominee Mike Braun Joe Donnelly Party Republican Democratic Popular vote 1,158,000 1,023,553 Percentage 50.73% 44.84%
County results Braun:     40–50%     50–60%     60–70%     70–80% Donnelly:     40–50%     50–60%     60–70%
U.S. senator before election Joe Donnelly Democratic Elected U.S. senator Mike Braun Republican

One-term DemocratJoe Donnelly was elected with 50.04% of the vote in 2012. He ran. He won the Democratic primary unopposed.^[46]

State RepresentativeMike Braun^[46] won the May 8 Republican primary. U.S. RepresentativesLuke Messer^[47] andTodd Rokita^[47] also ran for the Republican nomination.

James Johnson ran as an independent.^[46]

Braun won election with 51% of the vote, defeating Joe Donnelly.^[48]

Maine election

← 2012 2024 →
Turnout	59.96%
Nominee Angus King Eric Brakey Zak Ringelstein Party Independent Republican Democratic Popular vote 344,575 223,502 66,268 Percentage 54.31% 35.23% 10.45%
County results Municipality results King:     40–50%     50–60%     60–70%     70–80%     80–90%     >90% Brakey:     40–50%     50–60%     60–70%     70–80%     80–90%     >90% Tie:
U.S. senator before election Angus King Independent Elected U.S. senator Angus King Independent

One-term Independent SenatorAngus King was elected in a three-way race with 53% of the vote in 2012. King has caucused with theDemocratic Party since taking office in 2013, but he has left open the possibility of caucusing with the Republican Party in the future.^[49]

State SenatorEric Brakey ran unopposed for the Republican nomination.^[50]

Public school teacher and founder of UClass Zak Ringelstein ran unopposed for the Democratic nomination.^[50]

The election was conducted withranked choice voting, as opposed to "First-past-the-post voting", after Maine voters passeda citizen referendum approving the change in 2016^[51] and a June 2018 referendum sustaining the change.^[52]

King was easily re-elected with over 50% of the vote.

Maryland election

← 2012 2024 →
Turnout	58.17%
Nominee Ben Cardin Tony Campbell Party Democratic Republican Popular vote 1,491,614 697,107 Percentage 64.86% 30.31%
Cardin:     40–50%     50–60%     60–70%     70–80%     80–90%     >90% Campbell:     50–60%     70–80%
U.S. senator before election Ben Cardin Democratic Elected U.S. senator Ben Cardin Democratic

Two-term DemocratBen Cardin was re-elected with 56% of the vote in 2012. He won the Democratic primary.^[53]

Tony Campbell, Evan Cronhardt, Nnabu Eze, Gerald Smith, and Blaine Taylor^[54] were seeking the Republican nomination, with Campbell winning.

Arvin Vohra, vice chairman of theLibertarian National Committee, sought the Libertarian Party nomination.^[54]

IndependentsNeal Simon^[54] and Edward Shlikas^{[citation needed]}, and Michael B Puskar ran.

Cardin won re-election to a third term in office.^[55]

Massachusetts election

← 2012 2024 →
Turnout	59.17%
Nominee Elizabeth Warren Geoff Diehl Party Democratic Republican Popular vote 1,633,371 979,210 Percentage 60.34% 36.17%
County results Municipality results Warren:     40–50%     50–60%     60–70%     70–80%     80–90%     >90% Diehl:     40–50%     50–60%     60–70%
U.S. senator before election Elizabeth Warren Democratic Elected U.S. senator Elizabeth Warren Democratic

One-term DemocratElizabeth Warren was elected with 54% of the vote in 2012. She ran for re-election.^[56]

State RepresentativeGeoff Diehl,^[57] attorney and founder ofBetter for America,John Kingston^[57] and former Romney aide Beth Lindstrom,^[57] ran for the Republican nomination. Diehl won the Republican nomination.

Shiva Ayyadurai^[58] ran as an independent. Shiva started as in early 2017 as the first Republican in the race, but went independent in November 2017.

Warren defeated Diehl, winning a second term.^[59]

Michigan election

← 2012 2024 →
Turnout	56.72%
Nominee Debbie Stabenow John James Party Democratic Republican Popular vote 2,214,478 1,938,818 Percentage 52.26% 45.76%
Stabenow:     40-50%     50–60%     60–70%     70–80% James:     40–50%     50–60%     60–70%     70–80%
U.S. senator before election Debbie Stabenow Democratic Elected U.S. senator Debbie Stabenow Democratic

Three-term DemocratDebbie Stabenow was re-elected with 59% of the vote in 2012.^[60] She was renominated without Democratic opposition. On the Republican side, businessmanJohn James won the nomination.^[60]

In the final months of the election, polls showed the race was beginning to narrow. Ultimately, Stabenow was re-elected, defeating James, with a majority of the vote.

Minnesota general election

← 2012 2024 →
Turnout	63.89%
Nominee Amy Klobuchar Jim Newberger Party Democratic (DFL) Republican Popular vote 1,566,174 940,437 Percentage 60.31% 36.21%
Klobuchar:     40–50%     50–60%     60–70%     70–80% Newberger:     40–50%     50–60%     60–70%
U.S. senator before election Amy Klobuchar Democratic (DFL) Elected U.S. senator Amy Klobuchar Democratic (DFL)

Two-term DemocratAmy Klobuchar was re-elected with 65% of the vote in 2012. She ran for re-election.^[61]

State RepresentativeJim Newberger^[61] ran for the Republican nomination.

Klobuchar was easily re-elected.^[62]