Representative Nancy Mace, once a moderate Republican who made a full-bore turn to Trumpism, announced on Monday that she would enter the crowded 2026 contest for governor of South Carolina.

Ms. Mace, 47, is one of the highest-profile Republicans to join the race. Still, the candidate pool is already filled with big names in the state, including Alan Wilson, South Carolina’s longtime attorney general; Pamela Evette, the state’s lieutenant governor; and Representative Ralph Norman, one of the most conservative members of the U.S. House. The incumbent governor is barred from seeking another term.

Ms. Mace has hinted about running for the office for some time. She made her decision public Monday on social media, on the cable TV talk show Fox & Friends and at a morning event in Charleston, which is part of her competitive House district. She has been keeping the White House informed of her plans, though it was not clear whether President Trump would endorse her.

Ms. Mace said in an interview Sunday afternoon that she was prepared to be a “super MAGA governor,” referring to the pro-Trump Make American Great Again movement. “It’ll be Trump in high heels,” she said.

South Carolina’s electorate is one of the most conservative in the country, so whoever wins the Republican primary next spring will probably win the general election as well.

South Carolina gave Mr. Trump his first primary victory in 2016, helping propel him to the presidency. Gov. Henry McMaster, a Republican who was lieutenant governor at the time, was one of the first state politicians in the country to endorse Mr. Trump. And Mr. Trump has easily won the state, one of the fastest growing in the country, three times.