Donald Trump, a member of the Republican Party, sought re-election in the 2020 United States presidential election. He was inaugurated as president of the United States on January 20, 2017, and filed for re-election with the Federal Election Commission (FEC) on the same day. This was Trump's third run for President, his second with the Republican Party, and the only campaign Trump ran as an incumbent.

Trump began his re-election campaign unusually early for an incumbent president, beginning to spend money on the re-election effort within weeks of his election. From February 2017 onward, Trump held more than 150 rallies and fundraisers for this campaign, visiting key electoral states. The campaign also raised funds and ran two nationwide advertising campaigns. Trump said in several stump speeches that the slogans for the 2020 race would be "Keep America Great" and "Promises Made, Promises Kept". On November 7, 2018, Trump confirmed that Mike Pence would be his vice presidential running mate in 2020.

Trump's 2020 re-election bid was ultimately unsuccessful; the Democratic Party ticket of Joe Biden and Kamala Harris won the 2020 election. This marked the first time since 1992 that an incumbent president lost reelection. Trump refused to accept the results; he and his allies made disproven claims of fraud, pressured elections officials, filed several unsuccessful lawsuits, and directly attempted to overturn the results at the county, state, and federal level. This culminated in the attack on the United States Capitol on January 6, 2021, for which Trump was impeached a second time. The day after the attack, Trump stated that a "new administration" would be succeeding his, without mentioning president-elect Biden by name, in a video posted on Twitter. Had Trump been re-elected to a second consecutive term in 2020, he would have been the oldest U.S. president to be elected president twice at the age of 74 years, 4 months, and 20 days, surpassing Ronald Reagan in 1984, also if he had won in 2020 he would not have been eligible to run again in 2024 due to term limits set by the 22nd Amendment to the United States Constitution. Trump subsequently ran for a re-election campaign four years later in 2024 in which this was allowed as he was still only elected once prior to the 2024 United States presidential election, and was successfully elected to a second non-consecutive term as the 47th president of the United States, and Pence was replaced by JD Vance as his running mate and subsequently elected as the 50th vice president.

Trump's predecessors merged their campaign committees into their party's committee following their election victories. Following his 2016 election victory, Trump eschewed this presidential tradition and retained a separate campaign committee which continued raising funds. In December 2016, the campaign raised $11 million. These moves indicated that Trump was already eyeing a 2020 run.

Trump started spending money on the 2020 race on November 24, 2016 (sixteen days after the end of the 2016 election). The earliest campaign disbursement that his committees reported was spent towards the 2020 presidential primaries was for the purchase of a Delta Air Lines ticket on this date. Trump officially filed his re-election campaign with the FEC on January 20, 2017, the day of his inauguration. Trump launched his re-election campaign earlier in his presidency than his predecessors did. Barack Obama (2012), George W. Bush (2004), Bill Clinton (1996), George H. W. Bush (1992) and Ronald Reagan (1984) all declared their candidacies for reelection in the third year of their presidencies. His immediate successor, Joe Biden (2024), also declared his candidacy for reelection in the third year of his presidency. Trump filed the papers for his re-election campaign approximately 47 months prior to the date of the election. In contrast, both Reagan and George H. W. Bush did so approximately twelve, George W. Bush approximately eighteen, and both Clinton and Obama (and later Biden) approximately nineteen months before those elections.

While previous presidents had held rallies in the early days of their presidency to garner support for legislation, such rallies differed from Trump's in that they were funded by the White House rather than by campaign committees. One of the advantages of having his campaign committee fund the events is that organizers can more discriminately screen attendees, refusing entry to non-supporters. Trump's February 2017 rally in Melbourne, Florida, was the earliest campaign rally for an incumbent president.

By filing for his campaign as early as he did, Trump gave himself a head start on fundraising. This theoretically helped discourage primary challengers.

Since his three predecessors (Bill Clinton, George W. Bush, and Barack Obama) won re-election, had Trump been reelected, it would have been the first time in American history that four consecutive presidents were elected to two consecutive terms.