Nikki Haley will address the state of the race today.

Nikki Haley, the former South Carolina governor who polls indicate is badly trailing Donald J. Trump with her home state’s primary just days away, will hold a campaign event today addressing the state of the race.

“I’m not going to give up,” she said on Sunday in Rock Hill, S.C., southwest of Charlotte, N.C., to loud applause. “Why would I give up when 70 percent of Americans have said they don’t want Trump or Biden in this election? Why would I give up when 59 percent of Americans say Donald Trump is too old and Joe Biden is too old?”

After Tuesday’s event, which is set to take place at noon, Ms. Haley will hold a campaign rally later in the day, and she has other campaign events scheduled through the South Carolina primary, on Saturday. She has previously indicated that she intends to stay in the race through Super Tuesday, on March 5, when several crucial states, including California and Texas, will hold their nominating contests.

But Ms. Haley is in a precarious position in the race. Mr. Trump, who has a Fox News town-hall event set to be broadcast on Tuesday night, is on track for a decisive victory in the South Carolina primary, according to recent polling, and his position looks even stronger in some of the states that follow. Recent polls of Republicans in Texas, for example, show Ms. Haley with less than 20 percent support and Mr. Trump with 80 percent. A national survey of Republican voters last week by The Economist and YouGov showed Ms. Haley with less than 10 percent support and Mr. Trump with 80 percent support.

With just four days remaining until the South Carolina primary, Ms. Haley has sought to sharpen her contrasts with Mr. Trump, portraying his legal troubles as an insurmountable liability and predicting