CHARLESTON, S.C. (AP) — Nikki Haley, the former South Carolina governor and United Nations ambassador, announced her candidacy for president on Tuesday, becoming the first major challenger to former President Donald Trump for the 2024 Republican nomination.

The announcement, delivered in a video, marks an about-face for the ex-Trump Cabinet official, who said two years ago that she wouldn’t challenge her former boss for the White House in 2024. But she changed her mind in recent months, citing, among other things, the country’s economic troubles and the need for “generational change,” a nod to the 76-year-old Trump’s age.