“I’m Nikki Haley and I’m running for president,” Haley said in a video that her team sent out by email.

Haley, a former South Carolina governor who served as Trump’s U.S. ambassador to the United Nations, will lay out her campaign plans in a speech in Charleston, South Carolina, on Wednesday.

She became Trump’s first direct challenger in a Republican field expected to grow in coming weeks and months.

Other high-profile Republicans looking at a 2024 run include Florida Governor Ron DeSantis, former Vice President Mike Pence, U.S. Senator Tim Scott of South Carolina, New Hampshire Governor Chris Sununu and former Arkansas Governor Asa Hutchinson, among others.

“It’s time for a new generation of leadership – to rediscover fiscal responsibility, secure our border, and strengthen our country, our pride and our purpose,” Haley said in her video.

She also harked back to her foreign policy experience.

“China and Russia are on the march. They all think we can be bullied, kicked. You should know this about me: I don’t put up with bullies. And when you kick back, it hurts them more if you’re wearing heels,” she said.

By Steve Holland and Susan Heavey

(Reporting by Steve Holland and Susan Heavey; Editing by Doina Chiacu and Nick Macfie)