2016 United States Senate elections

The 2016 United States Senate elections were held on November 8, 2016. The presidential election, House elections, 14 gubernatorial elections, and many state and local elections were held on the same date.

In the elections, 34 of the 100 seats—all Class 3 Senate seats—were contested in regular elections; the winners will serve six-year terms until January 3, 2023. Class 3 was last up for election in 2010, when Republicans won a net gain of six seats.

In 2016, Democrats defended 10 seats, while Republicans defended 24 seats. Republicans, having won a majority of seats in the Senate in 2014, held the Senate majority with 54 seats before this election. Although Democrats made a net gain of two seats and did not lose any of their seats, Republicans retained control of the Senate for the 115th United States Congress. The two Democratic gains came from the defeats of incumbents Kelly Ayotte in New Hampshire and Mark Kirk in Illinois by Democrats Maggie Hassan and Tammy Duckworth, respectively.

Despite Republicans retaining control of the Senate, 2016 marked the first time since 1986 where Democrats made a net gain of seats in Class 3. This is also the only election cycle since the popular-vote election of senators was mandated by the Seventeenth Amendment in 1913 that the winning party in every Senate election mirrored the winning party for their state in the presidential election. This feat had nearly been accomplished earlier in 1920, which also involved the Class 3 Senate seats, and nearly repeated in 2020; in both cases, every state, with the exception of Kentucky in 1920 and Maine in 2020, voted for the same party in the presidential election and their Senate election. In addition, this election marked the first time since 2000 in which the party in opposition to the elected or reelected presidential candidate made net gains in the Senate; both cases involved the election of a Republican president and the Democrats making gains in the Senate.

With the retirement of Harry Reid, Chuck Schumer became the Democratic leader after the elections, while Mitch McConnell retained his position as Senate Majority Leader.

As of 2022, this is the most recent election cycle in which Republicans won Senate races in Arizona, Georgia, or Pennsylvania. It is also the most recent election cycle where there were no special elections.

Results summary

All 34 Class 3 senators were up for election in 2016; Class 3 consisted of 10 Democrats and 24 Republicans. Of the senators not up for election, 34 of the senators not up for election were Democrats, 30 senators were Republicans, and two senators were independents who caucused with the Senate Democrats.

Source: Clerk of the U.S. House of Representatives

Change in composition

Before the elections

After the elections

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 reelection) 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%

The New York Times's ''Upshot'' gave the Democrats a 60% chance of winning the Senate on August 24, 2016; on September 23, their model gave Republicans a 58% chance to maintain control.

Primary dates

This table shows the primary dates for regularly-scheduled elections. It also shows the type of primary.
* "Open" primary: any registered voter can vote in any party's primary
* "Closed" primary, only voters registered with a specific party can vote in that party's primary.
* " Top-two" primary, all candidates run against each other regardless of party affiliation, and the top two candidates advance to the second round of voting. (In Louisiana, a candidate can win the election by winning a majority of the vote in the first round.)
* All of the various other primary types are classified as "hybrid." Alaska in 2008 provides one example of a hybrid primary: The Democratic Party allowed unaffiliated voters to vote in its primary, while the Republican Party only allowed party members to vote in its primary.

Indicates a state that requires primary run-off elections under certain conditions.

Retirements and defeats

Retirements

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

Defeats

Two Republicans sought re-election but lost in the general election.

Race summary

Elections leading to the next Congress

In these general elections, the winners were elected for the term beginning January 3, 2017; ordered by state.

All of the elections involved the Class 3 seats.

Closest races

Nine races had a margin of victory under 10%:

Alabama

Incumbent Republican Richard Shelby won re-election to a sixth term in office. The primaries were held on March 1. Ron Crumpton, a marijuana legalization activist, was the Democratic nominee. Shelby won re-election with 63.9% of the vote.

Shelby was first elected to the Senate in 1986 as a Democrat and was easily re-elected in 1992 as such. He switched his party affiliation to Republican on November 9, 1994, one day after the Republicans won control of both houses in the midterm elections. He won his first full term as a Republican in 1998 by a large margin and faced no significant opposition in 2004 or 2010.

Following the divisive Republican primary in Mississippi ahead of the 2014 election in which Senator Thad Cochran was almost defeated, it had been speculated that Shelby could also face a Tea Party primary challenger, due to his lengthy tenure and support for federal largesse. However, that didn't happen, in part due to his large campaign war chest, which stood at $19.4 million as of September 2015. If Shelby had decided to retire, numerous high-profile Alabama Republicans were speculated to run, including U.S. Representatives Robert Aderholt, Mo Brooks, Bradley Byrne, Gary Palmer, Martha Roby, and Mike Rogers, State Treasurer Young Boozer, State Speaker Mike Hubbard, Lieutenant Governor Kay Ivey, State Senate President Pro Tempore Del Marsh, Secretary of State John Merrill, U.S. Appeals Court Judge William H. Pryor Jr., former Governor Bob Riley, and Attorney General Luther Strange. Shelby announced in January 2015 that he would run for re-election.

Alaska

Two-term Senator Lisa Murkowski (Republican) was appointed in 2002 and elected to a full term in 2004. She was defeated in the Republican primary in 2010 by Joe Miller. She later ran as a write-in candidate in the 2010 general election and was re-elected to a second full term with 40% of the vote, making her one of two senators in US history to win election via write-in votes. She was 59 years old in 2016. She ran for re-election.

Thomas Lamb, a candidate for the State House in 2006, and Bob Lochner filed to run against Murkowski. Other potential Republican primary challengers included 2010 nominee and 2014 candidate Joe Miller, State Senator Mike J. Dunleavy, former Lieutenant Governor Mead Treadwell, and former Mayor of Anchorage Dan Sullivan.

The only person to file for the Democratic primary as of May 20 was writer and satirist Richard Grayson, who previously sought election to Wyoming's House seat in 2014. Potential Democratic candidates included State Senator Dennis Egan, State Representative Andy Josephson, State Senator Bill Wielechowski, State Senator Hollis French and State Senate Minority Leader Johnny Ellis. Former Senator Mark Begich was mentioned as a possible candidate, but he declined to run.

Murkowski won her primary on August 16, 2016 with 72 percent of the vote. Joe Miller received the Libertarian nomination and ran against Murkowski in the general election. Anchorage attorney and veteran Margaret Stock ran as an Independent candidate.

Murkowski won re-election with 44% of the vote compared to Miller with 30% and Metcalfe with 11%. 15% went to other candidates. Murkowski has been re-elected three times now with 48% in 2004, 39.5% in 2010 and 44% in 2016, never having won a majority.

Arizona

Five-term Senator and Republican presidential candidate in 2008 John McCain was re-elected with 59% of the vote in 2010. He was 80 years old in 2016. Despite speculation that he might retire, McCain ran for re-election.

McCain faced primary challenges from Fair Tax activist Alex Meluskey, businessman David Pizer, talk radio host Clair Van Steenwyk, and State Senator Kelli Ward. David Pizer later dropped out of the race. Representatives Matt Salmon and David Schweikert were both mentioned as possible candidates, but both chose not to run. Other potential Republican candidates included former Governor Jan Brewer, businesswoman and 2014 gubernatorial candidate Christine Jones, former Governor of Alaska and 2008 vice presidential candidate Sarah Palin, former U.S. Representative John Shadegg, and former Arizona Attorney General Grant Woods.

Congresswoman Ann Kirkpatrick and teacher Lennie Clark ran for the Democratic nomination. Lennie Clark dropped out and Ann Kirkpatrick became the Democratic nominee. Other potential Democratic candidates included U.S. Representative Ruben Gallego, former Surgeon General and 2012 nominee Richard Carmona, 2014 gubernatorial nominee Fred DuVal, Phoenix Mayor Greg Stanton, and retired astronaut Mark Kelly, who is the husband of ex-Congresswoman Gabby Giffords.

Sen. McCain won re-election with 53% to Kirkpatrick's 41%.

Arkansas

One-term Senator John Boozman (Republican) defeated two-term Senator Blanche Lincoln with 58% of the vote in 2010. He was 65 years old in 2016. Despite speculation that he might retire following health problems, Boozman ran for re-election. Fellow Republican Curtis Coleman, who ran against Boozman in 2010 but came in fifth place, ran again.

Conner Eldridge, the former U.S. Attorney for the Western District of Arkansas, is the only Democrat who met the filing deadline.

Frank Gilbert was the candidate for the Libertarian Party, and Jason Tate was running a write-in campaign.

Incumbent Republican Senator John Boozman won re-election to a second term in office, becoming the first Republican senator re-elected in the history of the state.

Sen. Boozman won re-election with 60% to Eldridge's 36%.

California

Four-term Senator Barbara Boxer (Democrat) was re-elected with 52% of the vote in 2010. Boxer declined to run for re-election. California Attorney General Kamala Harris and U.S. Representative Loretta Sanchez, both Democrats, finished first and second, respectively, in California's nonpartisan blanket primary, and contested the general election. As such, Boxer's successor was guaranteed to be a Democrat. This marked a historic first such occasion in California, ever since the Senate elections began in 1914.

Other Democrats on the primary ballot included "President" Cristina Grappo, Massie Munroe, Herbert Peters, Emory Rogers, and Steve Stokes. Among the potential candidates who declined to run were Governor Jerry Brown, Lieutenant Governor Gavin Newsom, U.S. Representatives Xavier Becerra and Adam Schiff, and Los Angeles Mayor Eric Garcetti.

Former state Republican Party chairs Tom Del Beccaro and Duf Sundheim, and former State Senator Phil Wyman ran, along with Don Krampe, Tom Palzer, Karen Roseberry, Greg Conlon, Von Huogo, Jerry Laws, Ron Unz, Jarrell Williamson, and George Yang. State Assemblymen Rocky Chavez was running as well, but withdrew from the race. Republicans who were once considered potential candidates but ruled out runs included San Diego Mayor Kevin Faulconer, former Assistant Secretary of the Treasury for Financial Stability and 2014 gubernatorial nominee Neel Kashkari