2020 Democratic Party presidential primaries

Presidential primaries and caucuses were organized by the Democratic Party to select delegates to the 2020 Democratic National Convention to determine the party's nominee for president in the 2020 election. The primaries and caucuses took place in all 50 U.S. states, in the District of Columbia, in five U.S. territories, and through Democrats Abroad. They occurred between February 3 and August 11, 2020.

Former vice president Joe Biden led in the polls throughout most of 2019. The 2020 Iowa Democratic presidential caucuses were marred by technical problems; certified results of the caucus eventually showed Mayor Pete Buttigieg winning the most delegates, while Senator Bernie Sanders won the popular vote in the state. Sanders then won New Hampshire and Nevada. Biden, whose campaign fortunes had suffered from losses in Iowa, New Hampshire and Nevada, made a comeback by overwhelmingly winning the South Carolina primary. After Biden won South Carolina, and one day before the Super Tuesday primaries, several candidates dropped out of the race and endorsed Biden. Biden then won 10 out of 15 contests on Super Tuesday.

On April 8, after Sanders withdrew from the race, Biden became the presumptive Democratic presidential nominee. Biden and his running mate, U.S. senator Kamala Harris of California, were nominated for president and vice president by delegates at the Democratic National Convention. Biden and Harris won the presidency and vice presidency in the general election on November 3, defeating incumbent President Donald Trump and incumbent Vice President Mike Pence.