Joe Biden served as president of the United States from 2021 to 2025, vice president from 2009 to 2017, and in the United States Senate from 1973 until 2009. A member of the Democratic Party, he made his second presidential run in 2008, later being announced as Democratic presidential nominee Barack Obama's running mate in 2008. He was elected vice president in 2008 and re-elected in 2012. In April 2019, Biden announced his 2020 presidential campaign. He became the presumptive Democratic nominee in April 2020, was formally nominated by the Democratic Party in August 2020, and defeated Republican incumbent Donald Trump in the November 2020 election.

Over his career, Biden has generally been regarded as belonging to the mainstream of the Democratic Party. Biden has been described as center to center-left, and has described himself as the latter. Figures farther to the left such as Bernie Sanders have criticized Biden for not embracing Medicare for All or the Green New Deal. Biden's policies emphasize the needs of middle-class and working-class Americans, and have drawn political support from those groups. Biden has supported campaign finance reform including the Bipartisan Campaign Reform Act and overturning Citizens United; the 1994 Violent Crime Control and Law Enforcement Act; the American Recovery and Reinvestment Act of 2009; student tax credits; carbon emissions cap and trade; the increased infrastructure spending proposed by the Obama administration; mass transit; renewable energy subsidies; student loan forgiveness; and reversals of Republican tax cuts for the wealthy and corporations. He supports building upon the Affordable Care Act through a public health insurance option instead of a single-payer system. He supports decriminalizing cannabis at the federal level and the right for states to legalize it. Biden has been publicly in favor of same-sex marriage since 2012 when he became the highest-ranking U.S. official to voice support for same-sex marriage, preempting Obama on the subject. He also supports the Roe v. Wade decision and since 2019 has been in favor of repealing the Hyde Amendment.

In a 2019 article about Biden's record on abortion, his press secretary Jamal Brown said that when Biden arrived in the Senate in 1973 he thought Roe v. Wade was wrongly decided, but now "firmly believes that Roe v. Wade is the law of the land and should not be overturned". In 1981, he voted for a failed constitutional amendment allowing states to overturn Roe v. Wade. In 1982, he voted against the same failed constitutional amendment allowing states to overturn Roe, and in 2006, he stated in an interview that "I do not view abortion as a choice and a right. I think it's always a tragedy[.]" He now says he would consider codifying the Roe precedent into federal law in case the United States Supreme Court overturns the ruling. He pledged that he would appoint United States Supreme Court justices who shared his beliefs in upholding Roe.

From 1976 to June 5, 2019, Biden supported the Hyde Amendment. On June 6, 2019, Biden reversed his support and now supports repealing the Hyde Amendment. In 1981, he voted to end federal funding for abortion for victims of rape and incest. Biden previously supported the Mexico City policy, but now supports repealing it.

Despite voting for the Partial-Birth Abortion Ban Act of 2003, he opposed the 2007 United States Supreme Court ruling in Gonzales v. Carhart which upheld the act. He later clarified that he agreed with the decision but not the court's reasoning.

In the mid-1970s, Biden was one of the Senate's leading opponents of race-integration busing. His Delaware constituents strongly opposed it, and such opposition nationwide later led his party to mostly abandon school integration policies.

In his first Senate campaign, Biden expressed support for busing to remedy de jure segregation, as in the South, but opposed its use to remedy de facto segregation arising from racial patterns of neighborhood residency, as in Delaware; he opposed a proposed constitutional amendment banning busing entirely. In May 1974, Biden voted to table a proposal containing anti-busing and anti-desegregation clauses but later voted for a modified version containing a qualification that it was not intended to weaken the judiciary's power to enforce the 5th Amendment and 14th Amendment.

Later, Biden was heckled at a meeting of Delaware anti-busing parents over his opposing vote on a Senate bill that would have created criteria for busing mandates that restricted their use to only certain situations, such as to remedy de jure and not de facto segregation, and "that would have permitted jurisdictions facing [busing] to return to court and possibly have their busing mandate vacated" if the mandate didn't meet those criteria. Biden believed it would be better for the courts, instead of a law, to define such criteria for busing mandates. Despite this, the prospect of a busing plan in Wilmington, along with his opposition to busing requirements outside of de jure segregated areas, led Biden to align himself with anti-busing senators. In 1975, he supported a proposal that would have prevented the Department of Health, Education, and Welfare from cutting federal funds to districts that refused to integrate; he said busing was a "bankrupt idea [violating] the cardinal rule of common sense" and that his opposition would make it easier for other liberals to follow suit. At the same time he supported initiatives on housing, job opportunities, and voting rights.