The 2020 presidential campaign of Kamala Harris, a United States senator from California from January 2017 to 2021, officially began on January 21, 2019, with an announcement on Good Morning America. Harris had widely been considered a "high profile" candidate for the 2020 Democratic Party presidential primaries since 2016. Citing a lack of funds, Harris officially withdrew her candidacy on December 3, 2019.

On March 8, 2020, Harris endorsed former vice president Joe Biden. Eight months after the conclusion of her campaign, Harris was chosen by Democratic nominee Biden to be his running mate on August 11, 2020. Biden and Harris would went on to win the general election, and were sworn in on January 20, 2021, causing Harris to leave the Senate after 4 years, becoming the first female vice president of the United States. Biden initially ran for re-election in 2024 with Harris would remain his running mate but ultimately withdraw from the race and immediately endorsed Harris, who launched her second campaign for president later that day. Harris would go on to become the Democratic nominee, but lost the general election to Biden's predecessor, former president and Republican nominee Donald Trump, who became the 47th president of the United States. Biden and Harris served only one term in office.

Background Following the election of Donald Trump in November 2016, Harris was named as part of the "Hell-No Caucus" by Politico in 2018, along with Senators Cory Booker, Kirsten Gillibrand, Elizabeth Warren, and Bernie Sanders, given she voted "overwhelmingly to thwart [Trump's] nominees for administration jobs", such as with Rex Tillerson, Betsy DeVos, and Mike Pompeo; all the senators in this group were considered potential 2020 presidential contenders at this point in time. Prior to announcing her candidacy, she had publicly stated that she was "not ruling it out". In December 2018, Harris announced that she planned on considering whether to run for president "over the holiday". The following month, it was confirmed that Harris was expected to make an official announcement around Martin Luther King Jr. Day regarding the 2020 election.

Harris was the sixth office-holding Democrat to formally announce a campaign in the 2020 U.S. presidential election, joining Massachusetts senator Elizabeth Warren, Hawaii congresswoman Tulsi Gabbard, former Maryland congressman John Delaney, former West Virginia state senator Richard Ojeda, former U.S. secretary of housing and urban development Julian Castro, and New York senator Kirsten Gillibrand.

Prior to and during her presidential campaign, an online informal grouping using the hashtag #KHive formed to support her candidacy and defend her from racist and sexist attacks. Joy Reid first used the term in August 2017 in a tweet saying "@DrJasonJohnson @ZerlinaMaxwell and I had a meeting and decided it's called the K-Hive."

Campaign Announcement On Martin Luther King Jr. Day, January 21, 2019, Harris announced on Good Morning America that she would be seeking the Democratic presidential nomination. Her campaign headquarters were in Baltimore, Maryland, with a second office in Oakland, California. Her campaign slogan, "For the People", is the phrase she used to formally announce her appearances as a prosecutor in the California superior courts as implicitly required by California law.California Government Code Section 100 requires all prosecutions to be conducted in the name of the people and by their authority.

Within twenty-four hours of the announcement, Harris's campaign received over $1.5million in donations from about 38,000 individuals across all fifty states, with the average donation being $37. At the time, this record amount tied with the one set by U.S. senator Bernie Sanders during the 2016 election.

An overflow crowd of over 20,000 attended her formal campaign kickoff event at Frank Ogawa Plaza in her hometown of Oakland, California, on January 27. Numerous commentators noted that there were more attendees at Harris's kickoff event than Barack Obama's first presidential campaign kickoff in Springfield, Illinois, in 2007.

First quarter On January 28, Harris introduced herself as a 2020 presidential candidate in a CNN town hall at Drake University in Des Moines, Iowa.

In the first quarter of her campaign, Harris announced the endorsements of five members of the California delegation in the U.S. House of RepresentativesTed Lieu, Katie Hill, and Nanette Barragan on January 28, Barbara Lee on February 14, and Julia Brownley on February 27. Continuing her early show of force from her home state, Harris also secured the endorsement of the Governor of California, Gavin Newsom, along with five statewide officials from CaliforniaLieutenant Governor Eleni Kounalakis, Secretary of State Alex Padilla, State Treasurer Fiona Ma, Superintendent of Public Instruction Tony Thurmond, and Insurance Commissioner Ricardo Lara She also secured the endorsements from three-quarters of the Democratic delegation in the California State Senate, along with endorsements from the mayors of California cities San Francisco, San Jose, Sacramento, Long Beach, Oakland, and Compton. Harris also secured the support of former Massachusetts Attorney General Martha Coakley and Latina labor rights activist and co-founder of the United Farm Workers union, Dolores Huerta.

Harris came under criticism when, in February 2019, she immediately believed the Jussie Smollett hate crime hoax while the affair had already been strongly questioned by the Chicago Police Department. She called it a "modern-day lynching" and used it to push for the adoption of a law co-sponsored by her. The incident later turned out to be staged, and Harris had to walk back her comments. The Daily Beast asserted this was representative of her supposed "habit of making flip comments, and tending to latch on to narratives that confirm her preferred political worldview".

In March, Harris headlined a fundraiser from high-profile Hollywood donors at the home of American filmmaker J. J. Abrams and Katie McGrath. Co-chairs for the event included various other high-level studio executives, actors, writers, and directors, including Ari Emanuel, Donna Langley, Shonda Rhimes, and Ron Meyer. Harris reported raising $12million from more than 218,000 individual contributions in the first quarter.

Second quarter

On April 1, Harris delivered a speech at a labor dinner honoring state legislators in Sacramento, California, where she listed workers benefits that would not have been made possible without organized labor and condemned rhetoric that described unions as "special-interest groups".

On April 14, Harris released all her personal tax returns from 2004 to 2018, each year that Harris has held public office. A Harris campaign aide said Harris's disclosure made her "the most transparent candidate in the field when it comes to information about personal finances".

On May 5, Harris gave a speech at the Fight for Freedom Fund Dinner of the Detroit Branch NAACP in which she pledged that her administration would "hold social media platforms accountable for the hate infiltrating their platforms, because they have a responsibility to help fight against this threat to our democracy" and referred to 2018 as the "deadliest year on record for domestic terrorism" since the 1995 Oklahoma City bombing.

On May 16, Harris announced that her campaign had raised over $160,000 for abortion rights groups, following Alabama lawmakers approving a measure that outlawed almost all abortions including instances of rape or incest and imposed criminal penalties on doctors that had performed the procedure.

On June 1, Harris delivered remarks at a San Francisco forum sponsored by the liberal group MoveOn when an animal rights protester jumped on stage and grabbed the microphone out of Harris's hand while she was trying to talk about equal rights. Moderator Karine Jean-Pierre moved to stand between Harris and the protester until security guards escorted him offstage.

On June 26 and 27, the first debate of the primary season was held at the Arsht Center in Miami, Florida, hosted by NBC and MSNBC. It was split into two parts, with 10 candidates debating on June 26 and 10 other candidates debating on June 27; a random drawing placed Harris in the latter group of candidates. On June 27, at one point in the debate, Harris criticized her fellow candidates for talking over each other, saying "America does not want to witness a food fight. They want to know how we are going to put food on their table." Later, she criticized Joe Biden for his comments regarding his past work with segregationist Senators and his past opposition to busing. Her widely quoted comment was:

Harris's performance in the debate received praise from many in the media, with some journalists referring to her as the unofficial winner. Morning Consult and FiveThirtyEight worked together on polling that reported that Harris's support among Democrats went from about 8% before the debate to almost 17% after the debate. Harris raised $2million in donations in the first 24 hours after the debate, which is the highest amount of money that her campaign had raised in a 24-hour period to that date. President Donald Trump criticized Harris, saying she was given "too much credit" for her debate with Biden.

In the second quarter, Harris announced the endorsements of five members of the Congressional Black CaucusAl Green on June 20, Alcee Hastings on June 21, Lacy Clay on June 25, and Frederica Wilson and Danny Davis on June 30. She also secured the support of a member of the Congressional Hispanic Caucus when Jim Costa endorsed her on June 17. Harris also added to her support from California, securing the endorsements of nearly half the Democratic delegation in the California Assembly, including Speaker Anthony Rendon. Harris also secured the support of former member of the South Carolina House of Representatives Bakari Sellers.

Harris raised $12 million from more than 279,000 donors by the end of the second quarter.

Third quarter

On July 12, Harris appeared on The View, where she stated her position on illegal immigration was treating the subject as a "civil enforcement issue" that was concurrent with a secure border and not treating individuals who entered the U.S. illegally like criminals; before she stated her intent to discontinue multiple practices of the Trump administration as it related to the subject.

On July 29, Harris released her own version of Medicare For All, which set forth a longer transition period of 10 years to move from the current system to a single-payer system without raising taxes on the middle class. Her proposal contained a public option and also allowed private insurance companies to offer healthcare plans within a highly regulated Medicare system modeled after Medicare Advantage. The proposal gathered praise from former U.S. health and human services secretary Kathleen Sebelius but drew immediate criticism from supporters of Bernie Sanders.

On July 30 and 31, the second debate of the primary season was held at the Fox Theater in Detroit, Michigan, and hosted by CNN. Harris was assigned to participate in the second night of the second debate. On July 31, Harris defended her health care plan from claims by Joe Biden that it would cost $3trillion and eliminate employer-based insurance. She asserted that her plan would "bring healthcare to all Americans under a Medicare for All system", and disparaged his health care proposal as leaving about ten million Americans uninsured. Congresswoman Tulsi Gabbard attacked Harris over her record as Attorney General, notably her past positions on marijuana, cash bail, and parole reform. At more than fifteen minutes, Harris spoke for the second largest amount of time of the second night candidates.