On this platform, we have previously looked at US House Representatives who lost primary races. Likened by George Washington to a cooling saucer, the Senate may have less division and partisanship but that does not mean Senators have not been primaried, including the recently-deceased Joe Lieberman. 

    Similar: Jeremy Corbyn & 5 Other MPs Who Were Deselected

    Joe Lieberman (2006)

    (Photo: Palm Beach Post)

    By 2006, few Democrats were as well-established on a national level as Joe Lieberman, best known as Al Gore’s running mate in the 2000 presidential election. 

    The first Jew on a major presidential ticket, he continued served in the Senate up to 2006, during which time he alienated many voters and colleagues. 

    Ned Lamont. (Photo: New York Times)

    In that year’s primary, Lieberman was toppled by more progressive challenger Ned Lamont who won 52% of the vote, with the leading factor seemingly being Lieberman’s support for the Iraq War. 

    In spite of his loss, Lieberman vowed to run to keep his Senate seat, After the Republican candidate Alan Schlesinger effectively became persona non grata after a gambling scandal, Lieberman became the choice for many right-wing commentators and politicians. He ran on the label Connecticut for Lieberman and was aided in the campaign by top Bush strategist Karl Rove. 

    Reportedly outraising Lamont by more than 2:1, Lieberman emerged victorious with nearly 50% of the vote, garnering the majority of independent and Republican support. 

    2006-2012 would be his final term in the Senate, most notable for his successful efforts to repeal the Don’t Ask, Don’t Tell Act, which barred open discussion of LGBTQ+ members of the military. 

    The Independent Democrat continued to be a thorn in the Democrats’s side, drifting increasingly away from his old party. In 2008, he endorsed John McCain for president whilst a decade later he supported the primaried Joe Crowley against Alexandria Ocasio-Cortez before praising Kyrsten Sinema’s efforts to block President Biden’s Build Back Better plan. Before his death in 2024, he was also a notable supporter of the centrist, non-partisan No Labels political party. 

    Lisa Murkowski (2010)

    (Photo: Politico)

    In 2010, the Tea Party-aligned candidate Joe Miller knocked off moderate Republican Lisa Murkowski in the Alaska primary. 

    Losing by just over 2,000 votes, Murkowski was able to use the deep red state’s status in her favour when she decided to run a write-in campaign.   

    Her candidacy was still a long shot however, with Miller having attained the support of former Governor Sarah Palin, Senator John Cornyn, and conservative commentator Laura Ingraham.  

    Joe Miller. (Photo: NPR)

    In the end however, Murkowski triumphed, receiving over 100,000 write-in votes. The win made her only the second Senator to win election via a write-in candidacy, after Strom Thurmond in 1954. In the aftermath, she remarked: “Alaskans have chosen the path of unity, the deliberative path, the common-sense path.” 

    She again faced stiff competition in her ultimately successful 2022 re-election campaign. In the aftermath of January 6th, Murkowski voted to impeach Trump and was the only Republican Senator to do so up for re-election. Under a new 2020 ballot initiative, she faced a fellow Republican challenger, Kelly Tshibaka, who had the backing who former President Trump and the Alaska G.O.P. Murkowski nonetheless had cross-party support, with notables such as George Bush, Mitch McConnell, and Joe Manchin in Murkowski’s corner.  

    Arlen Specter (2010)

    (Photo: USA Today)

    In April 2009, five-term Republican Senator Arlen Specter switched party allegiance to the Democrats, reasoning that “as the Republican Party has moved farther and farther to the right, I have found myself increasingly at odds with the Republican philosophy and more in line with the philosophy of the Democratic Party.” He further cited 200,000 Pennsylvanian voters switching registration from Republican to Democrat in his reasoning. 

    Specter had long been out-of-step with his party, including his support for affirmative action, the recognition of illegal immigrants, and moderate stance on abortion. It was his vote in favour of President Obama’s $787 billion American Recovery and Reinvestment Act stimulus package that seemed to sink his chances though, with the move opposed by 70% of Pennsylvania Republicans as he fell far behind in his primary race against Pat Toomey, who he only narrowly defeated in the last cycle. 

    Joe Sestak. (Photo: Philadelphia Inquirer)

    As a Democrat, Specter opposed the Defense of Marriage Act and supported legislation to make forming a union easier. Yet this failed to convince Democrat voters. 

    Despite his backing from the local state party and White House – particularly Vice-President Biden – he lost to opponent Joe Sestak who got 53.8% of the vote.  

    Although a big boost for the party, his previous record was hard to live down, having voted for the Iraq War, opposed the Brady Bill – later voting against background checks and waiting periods, and had (in his own words) “flat-out demoli[shed]” Anita Hill in her 1987 testimony over Supreme Court nominee Clarence Thomas’s sexual impropriety. 

    Alan Dixon (1992)

    (Photo: New York Times)

    1992 saw incumbent Senator Alan Dixon lose his seat in a surprise result, one more shocking considering no Senator had been primaried in over a decade. 

    The Illinois Senator would be beaten by Carol Moseley Braun, who – upon winning the election – would become the first-ever African-American woman in the Senate. She would be the only female African-American in the chamber in the 20th century, with the only other person to match the feat being future Vice-President Kamala Harris. 

    Additionally, it was too a surprise for the moderate Dixon to be beaten considering his 30 or so previous instances of electoral success, which amounted to 43 years of serving in elected office. At the time, he was the Deputy Whip of the Democratic Senate Caucus, making him the third highest-ranking Democrat in the chamber. 

    Carol Moseley-Braun. (Photo: Britannica)

    Braun’s victory saw her emerge with a majority of 50,000 votes, taking 38.3% of the vote to the incumbent’s 34.6%. 

    In his autobiography, The Gentleman from Illinois: Stories from Forty Years of Elective Public Service, Dixon himself points to several factors that hindered his campaign. 

    The presence of a third party in the primary, that of Albert Hofeld, hurt Dixon. Not only was Hofeld, a multi-millionaire, able to run damaging attack ads, but his role as another moderate helped split the vote and allow the more progressive Braun to victory. Braun too was backed by the Mayor of Chicago Harold Washington and Senator Jesse Jackson. 

    Moreover, due to his important role in the Senate, Dixon only visited his home state on the weekends, perhaps leaving constituents feeling he had abandoned them. Dixon too notes a way of hostility to Congress, including incumbents, during that particular election cycle. 

    The most commonly cited factor however is Dixon’s vote in favour of confirming Justice Clarence Thomas to the Supreme Court the previous year. The vote was particularly controversial considering the allegations from former employee Anita Hill that Thomas had sexually harassed her.  

    Dixon has conceded that the vote “ensured” his loss whereas The Washington Post noted that “history shows us that voters turned on Alan Dixon for his vote on Clarence Thomas.” 

    Bob Bennett (2010)

    (Photo: Daily Utah Chronicle)

    In 2010, the aforementioned Murkowski was not the only victim of the Tea Party’s rise as Utah saw Senator Bob Bennett ousted at the primary stage. 

    He had been targetted by the hard-right for his supposed lack of conservatism. This includes his support to recognise the status of illegal immigrants, his support for the $700 billion bank bailout, and co-sponsoring a bipartisan effort to mandate health insurance coverage. 

    He too was criticised for his role on the Senate Appropriations Committee, responsible for ballooning government spending. Elsewhere, the pressure group Club for Growth spent $200,000 on dethroning Bennett, pointing out he had one of the worst attendance records, missing 30 votes that year. 

    Mike Lee. (Photo: Britannica)

    At the 2010 Utah Republican Convention in May, Bennett faced defeat in the second round, polling third at just 27%. The 3,452 delegates instead favoured Tim Bridgewater and Mike Lee, the latter of whom was victorious in the primary and would win the seat. 

    Lee was supported in the race by former Senator Rick Santorium, ex-House Majority Leader Dick Armey, and Libertarian firebrand Ron Paul. 

    Despite the Tea Party’s attacks on Bennett, he otherwise had a strong conservative record. For example, in 2006, he had a 93% approval rating among Republican primary voters. His re-election was supported by the American Conservative Union and National Rifle Association, with popular presidential candidate and former Governor Mitt Romney too throwing his weight behind him.  

    Richard Lugar (2012)

    (Photo: ABC News)

    The last Senator to be primaried was veteran legislator Richard Lugar, who lost re-election in 2012. 

    That year, the Tea Party set their sights on Lugar who was the longest-serving Senator in Indiana history and had not faced a primary challenge since winning the seat in 1976. 

    His time in the chamber was perhaps defined by his work on nuclear weapons, particularly his work across the aisle with Sam Nunn in regard to the dismantling of warheads in the former Soviet Union. He too had notable moments outside of the Senate such as a keynote speech at the 1972 Republican Convention and an under-the-radar presidential run in 1996. 

     By 2012 however, the 80-year-old stalwart was ejected by his own constituents.  

    The major reason cited was his perceived closeness to President Obama. “Obama’s favourite Republican”, critics labelled him. In 2008, Obama won Indiana, the first Democrat to do so since Lyndon B. Johnson. 

    He too supported the DREAM Act (which would grant residency to immigrants raised in the USA), voting in favour with Obama’s Supreme Court justices, and had an F-rating from the NRA. During the campaign, he was also under fire for not keeping his primary residence in Indiana, having moved in the 1970s. 

    Richard Mourdock. (Photo: CNN)

    State Treasurer Richard Mourdock easily won over Lugar, prevailing by over 20 points with the incumbent struggling to get over 40%. Sarah Palin and Rick Santorium were among those backing Mourdock. 

    The defeat of Lugar, who held the seat for six terms (36 years), was the first time a Senator of such longevity had lost a seat in 60 years. 

    The choice not to go with the more moderate Lugar turned out to be a misstep. Mourdock’s campaign was hampered by a claim that pregnancy from rape was “something that God intended.” Despite the Democrats not even staging a challenger in the deep-red state in 2006, they triumphed in 2010, marking the first Democrat to hold the seat since 1970.