Elections were held in the United States on November 6, 2012. Democratic President Barack Obama won reelection to a second term and the Democrats gained seats in both chambers of Congress, retaining control of the Senate even though the Republican Party retained control of the House of Representatives. As of 2024, this is the most recent election cycle in which neither the presidency nor a chamber of Congress changed partisan control, the last time the incumbent party won the presidential election, and the last time that the party that won the presidency simultaneously gained seats in both the House of Representatives and the Senate.

Obama defeated Republican nominee Mitt Romney to win a second term, taking 51.1 percent of the popular vote and 332 of the 538 electoral votes. Romney defeated Rick Santorum, Newt Gingrich, and several other candidates to win his party's nomination in the 2012 Republican primaries.

Democrats won a net gain of two Senate seats, retaining control of the chamber. In the first election held in the House of Representatives since the round of redistricting following the 2010 United States census, Democrats picked up eight seats but failed to gain a majority, despite winning the popular vote. In the gubernatorial elections, Republicans won a net gain of one seat. This was the first time since 1936 that a Democratic presidential candidate who won a second term also had Senate coattails in both occasions (although Franklin Roosevelt won a third and fourth term in 1940 and 1944 respectively, he lost Senate seats on both occasions). This is the third straight presidential election where the winner had coattails in both houses of Congress.

Various other state, territorial, and local races and referendums were held throughout the year. Three state referendums passed legalizing same-sex marriage, while Minnesota became the first state in history to reject a proposed state-level constitutional ban of same sex marriage. Two states approved and one rejected the legalization of recreational marijuana, and one more state voted to legalize marijuana for medical use. A referendum was also held in Puerto Rico regarding the future political status of the U.S. unincorporated territory. Following the Supreme Court's Citizens United decision, the 2012 election season became the most expensive in American history.

Despite various issues during this election cycle, ultimately little overall change occurred on both the Federal and the gubernatorial levels.

Many of the major issues of the 2012 election were the same as in both 2008 and 2010. Candidates and voters in 2012 were again focused on national economic conditions and jobs, record federal deficits, health care and the effects of the controversial Affordable Care Act, national security and terrorism, education, and energy.

Immigration reform and the controversial Arizona Senate Bill 1070, passed by the state in 2010 to enhance the power of Arizona's law enforcement agencies to investigate the immigration status of suspected illegal immigrants, also remained important issues. On June 25, 2012, the Supreme Court delivered its decision in Arizona v. United States, striking down three of the four provisions of Arizona's law.

In 2011, there were a series of demonstrations in Wisconsin, involving at its zenith as many as 100,000 protestors opposing the 2011 Wisconsin Act 10, also called the "Wisconsin budget repair bill." The legislation, passed by the Wisconsin Legislature on June 29, 2011, primarily impacted the following areas: collective bargaining, compensation, retirement, health insurance, and sick leave of the state's public sector employees.