Nikki Haley will suspend her presidential campaign Wednesday after being soundly defeated across the country on Super Tuesday, according to people familiar with her decision, leaving Donald Trump as the last remaining major candidate for the 2024 Republican nomination.

Three people with direct knowledge who spoke on the condition of anonymity because they weren't authorised to speak publicly confirmed Haley's decision ahead of an announcement scheduled for Wednesday morning.

Haley, a former South Carolina governor and UN ambassador, was Trump's first significant rival when she jumped into the race in February 2023. She spent the final phase of her campaign aggressively warning the GOP against embracing Trump, whom she argued was too consumed by chaos and personal grievance to defeat President Joe Biden in the general election.

Her departure clears Trump to focus solely on his likely rematch in November with Biden. The former president is on track to reach the necessary 1,215 delegates to clinch the Republican nomination later this month.

Haley's defeat marks a painful, if predictable, blow to those voters, donors and Republican Party officials who opposed Trump and his fiery brand of “Make America Great Again” politics.

She was especially popular among moderates and college-educated voters, constituencies that will likely play a pivotal role in the general election. It's unclear whether Trump, who recently declared that Haley donors would be permanently banned from his movement, can ultimately unify a deeply divided party.

Haley leaves the 2024 presidential contest having made history as the first woman to win a Republican primary. She beat Trump in the District of Columbia on Sunday and Vermont on Tuesday.

She had insisted she would stay in the race through Super Tuesday and crossed the country campaigning in states holding Republican contests. Ultimately, she was unable to knock Trump off his glide path to a third straight nomination.