Nikki Haley has proudly called herself the underdog in the Republican presidential nomination fight, telling South Carolina audiences over and over how she defeated, or at least outlasted, 12 other candidates, all of them men, and then adding, “I just have one more fella to catch.”

But in her race in South Carolina to catch that fellow, former President Donald J. Trump, she ran an exceptionally conventional campaign, crisscrossing the state in a bus, delivering her stump speech almost word for word, over and over, and seldom taking questions from the audience or the news media in attendance. Her guest speakers were local mayors and prosecutors.

As the campaign for her home state came to a close, ending in a swift victory for Mr. Trump on Saturday night, some campaign professionals question how such a cautious effort was ever going to shake up a nominating contest in which Mr. Trump had already won the Iowa caucuses and New Hampshire primary, and held a clear lead in South Carolina.

Lis Smith, who helped run the presidential campaign of Pete Buttigieg in 2020, putting a little-known former mayor of South Bend, Ind., on the political map, said that once Ms. Haley got the race down to a two-candidate contest, “there was a huge opportunity to make a splash.”

But in the state where she served as governor, Ms. Haley didn’t do much of what a candidate trying to close a yawning gap would do, Ms. Smith said — such as take questions from voters or pull stunts to grab press attention, like showing up at campaign events with surprise guests.

“If you are the underdog, if you are trying to drive the narrative, you have to understand what drives the media,” she said, “and you have to be willing to make news, not give set speeches.”

Ms. Haley’s lone “stunt,” a speech Tuesday billed as a major state of the race address, did capture headlines. After notice of the speech led to rumors that she was dropping out, Ms. Haley devoted the time to explaining why, despite the polls, she was not going anywhere. And she argued that she wants nothing from Mr. Trump, who has insisted that she will leave the race and endorse him.

Chip Felkel, a South Carolina Republican political consultant and Trump critic, agreed with Ms. Smith, expressing surprise that Ms. Haley held so few town-hall meetings to take questions from potential voters.

But, he said, the caution sprang from experience and belied Ms. Haley’s statement that she doesn’t care about her political future.

She was burned in New Hampshire when she was asked at a town-hall meeting what caused the Civil War and neglected to mention slavery, he said. Her interview this week with NBC News in which she suggested she agreed with an Alabama Supreme Court ruling that frozen embryos were protected human life offered Mr. Trump a chance to stake out a more broadly popular position on I.V.F. on Friday. He issued a statement saying he supported the availability of the fertility treatment nationwide and said Alabama should move quickly to protect access.

Given the hold that Mr. Trump has on Republican voters in conservative states like South Carolina, there may have been nothing she could do to change the trajectory of the race, Mr. Felkel added. Her caution could be read as preserving options for a future comeback, should Mr. Trump win the presidential nomination but lose the election in November.

“She says she’s got nothing to lose,” Mr. Felkel said, “but she’s acting like she does. She’s hedging her bets.”