2024 Republican Party presidential primaries

Presidential primaries and caucuses of the Republican Party took place within all 50 U.S. states, Washington, D.C., and five U.S. territories between January 15, 2024, and June 4, 2024. These elections selected most of the 2,429 delegates to be sent to the Republican National Convention. Former president Donald Trump was nominated for president of the United States for a third consecutive election cycle.

In 2023, a crowded field of candidates emerged, including Trump, Florida governor Ron DeSantis, former Ambassador to the United Nations Nikki Haley, and wealth management executive Vivek Ramaswamy. Trump maintained a consistent lead in primary polling since 2020. Among non-Trump candidates, DeSantis initially polled in a close second behind Trump, but his polling numbers steadily declined throughout 2023. Ramaswamy experienced a small polling bump in mid-2023, but this proved to be brief. Haley's campaign began attracting greater attention in the final months of 2023, though neither she nor any other candidate came close to Trump in polling. The Republican primaries were referred to as a "race for second" due to Trump's consistent lead in polls.

At the January 15 Iowa caucuses, Trump posted a landslide victory, with DeSantis narrowly beating out Haley for second place and Ramaswamy in a distant fourth. Following the Iowa caucuses, Ramaswamy and DeSantis dropped out of the race and endorsed Trump, leaving Trump and Haley as the only remaining major candidates. Trump then defeated Haley in the January 23 New Hampshire primary, albeit by a smaller margin of victory than he achieved in Iowa; he defeated Haley again in the February 24 South Carolina primary a month later. After Trump's overwhelming victories nationwide on Super Tuesday, Haley suspended her campaign on March 6, having only won Vermont and Washington, D.C. Her victory in the Washington, D.C. primary on March 3, 2024, made her the first woman ever to win a Republican Party presidential primary contest.

Some Republicans expressed concerns about Trump's candidacy due to his loss in 2020, his alleged role in inciting the January 6 Capitol attack, ongoing criminal cases against him, and the results of the 2022 midterms in which several Trump-endorsed candidates lost key races; many others supported him and decried the investigations as politically motivated, and Trump maintained high favorability ratings among Republican voters. Trump's eligibility to appear on the ballot was challenged by some voters and political leaders in Colorado, Maine and Illinois; these efforts were rejected by the Supreme Court of the United States in a unanimous decision. Trump became the presumptive nominee on March 12, with his victory in the Washington primary bringing him over the 1,215 delegate threshold needed to clinch the nomination.

On July 15, 2024, Trump and his running mate, U.S. Senator from Ohio JD Vance, were officially nominated as the Republican presidential and vice presidential candidates at the Republican National Convention. Trump became only the second presidential candidate to be nominated by the Republican Party three times, after Richard Nixon, as well as the first person to ever be the Republican nominee in three consecutive elections. The Trump-Vance ticket won the general election on November 5, defeating the Democratic Party ticket of incumbent Vice President Kamala Harris and her running mate, Minnesota governor Tim Walz.