AP Decision Notes: What to expect in the South Carolina Republican presidential primary

Donald Trump and Nikki Haley will face off Saturday in South Carolina’s first-in-the-South Republican presidential primary. It's their first head-to-head matchup since the New Hampshire primary a month ago. The contest takes place on Haley’s home turf. She was South Carolina's governor for six years before stepping down in 2017 to serve as U.N. ambassador when Trump was elected president. But Haley faces strong headwinds in a state where Trump has the support of most of the party establishment. Trump held a substantial lead in recent polls and enjoys high popularity among the conservative base.