Incumbent President Joe Biden had repeatedly expressed his intent to run for re-election since 2021, although there was speculation in the first two years of his presidency that he might not seek a second term due to his age and low approval ratings.[17][18] Former Democratic House representatives, including Carolyn Maloney,[19]Joe Cunningham,[20] and Tim Ryan,[21] had publicly said Biden should not run. On July 28, 2022, Representative Dean Phillips became the first incumbent Democratic member of Congress to say President Biden should not run for re-election and called for "generational change" pointing to Biden's age.[22][23] There was also speculation that Biden might face a primary challenge, especially from a member of the Democratic Party's progressive faction.[24][25]
After Democrats outperformed expectations in the 2022 midterm elections, many believed the chances that Biden would run for and win his party's nomination had increased.[26][27] On April 25, 2023, Biden announced via a video that he would be running for re-election.[28] Eventually, three main primary opponents emerged; self-help author Marianne Williamson declared her candidacy in March,[29]Robert F. Kennedy Jr., an anti-vaccine activist and environmental attorney,[30] declared in April,[31] while Representative Dean Phillips of Minnesota declared in October.[32] Phillips campaigned as a younger alternative to Biden, who would be a stronger opponent to Trump.[33][34][35] Before launching his campaign, Phillips reportedly reached out to other elected Democratic officials, such as Governors Gretchen Whitmer and JB Pritzker, to convince them to enter the presidential primary race to oppose Biden, but they declined to speak with him directly.[36][37] Additionally, the Uncommitted National Movement, supported by some Muslim Americans, Arab Americans, progressives, and socialists began advocating in 2024 for an uncommitted vote in protest against Biden due to his support for Israel during the Israel–Hamas war.[38][39][40]
Kennedy withdrew from the Democratic primaries in October 2023 to run as an independent candidate.[41] Williamson suspended her campaign following the Nevada primary in February 2024,[42] before unsuspending her campaign following the Michigan primary later that month.[43] On March 6, 2024, Phillips suspended his campaign and endorsed Biden.[44] Phillips received the second-highest number of delegates in the primaries of any candidate (four delegates gained).[13][45] Biden lost American Samoa to venture capitalistJason Palmer,[f] becoming the first incumbent president to lose a contest while appearing on the ballot since Jimmy Carter in 1980.[46] However, he won every other contest by a large margin.
President Biden withdrew his candidacy on July 21, following a series of age and health concerns, writing that doing so was "in the best interest of my party and the country". He endorsed Vice President Kamala Harris as his successor.[47] And though Biden had endorsed Harris as the new candidate at the top of the ticket, there was no obligation for the delegates to follow suit.[48] By the next day, Harris had secured the non-binding support of enough uncommitted delegates that were previously pledged to Biden to make her the presumptive nominee.[49] Harris became the nominee following a virtual roll call with the support of approximately 97.21% of all the delegates and faced opposition from 52 delegates voting for other candidates which were counted as "present" as well as 79 abstentions, most notably from Representative Mary Peltola, Representative Jared Golden, and Senator Jon Tester.[50][51][52] Harris became the first Democratic nominee to be nominated despite not actively campaigning in the primaries since Hubert Humphrey in the 1968 United States presidential election, and the first to be nominated without winning the primaries since the modern Democratic Party primary procedure was created in 1972.
Harris and her running mate, Tim Walz, would ultimately lose the election to the Republican ticket of Donald Trump and JD Vance.[53]
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