With nine days until the first Republican presidential primary debate, the loyalty pledge required to appear on the stage is causing chaos as candidates opposed to President Trump, as well as Mr. Trump himself, take issue with the requirement.

The pledge in question states that the candidate will “honor the will of the primary voters and support the 2024 Republican presidential nominee in order to save our country and beat Joe Biden.”

A former governor of South Carolina, Nikki Haley, released a copy of the pledge after she became the first candidate to sign it last week.

“I further pledge that I will not seek to run as an independent or write-in candidate nor will I seek or accept the nomination for president of any other party,” the pledge reads.

Mr. Trump told Newsmax that he would decide on whether he plans to participate in the debate this week, making a point of saying that he wouldn’t sign the Republican National Committee’s loyalty pledge.

“Why would I sign a pledge?” the former president said. “There are people on there that I wouldn’t have. I wouldn’t have certain people as, you know, somebody that I’d endorse.”

Mr. Trump added, “I can name three or four people that I wouldn’t support for president. So right there, there’s a problem.”

Since then, Governor DeSantis, second in most primary polls to Mr. Trump, has attacked Mr. Trump, saying, “It’s not just about you,” adding, “It’s about a larger mission that we have to accomplish for Americans.”

“I mean you can’t, on the one hand, say that the country’s going in such a bad direction, which we all believe, and then, on the other hand, say you’re just going to take your ball and go home,” Mr. DeSantis told reporters in Iowa.

It’s clear that some candidates, like Governor Christie, are planning to get on the debate stage solely for the purpose of confronting Mr. Trump. Mr. Christie has publicly mocked the loyalty pledge in the past, and it looks likely he will continue to do so up until the debate, telling ABC that he thinks “this is all kind of nonsensical theater.”

“I’ve made that clear to the RNC as well, way back, even before I entered the race, that I thought the pledge was a bad idea, and Donald Trump is now playing that game,” Mr. Christie told ABC’s Jonathan Karl. “But that’s what he does. You know this, Jon. He plays misdirection all the time.”

Mr. Christie isn’t the only candidate opposed to Mr. Trump who has mocked the loyalty pledge. Congressman Will Hurd, who has not yet met the debate requirements but is perhaps the most outspoken critic of Mr. Trump in the campaign, has said he hopes to meet every requirement except the pledge requirement.

“I won’t be signing any kind of pledges, and I don’t think parties should be trying to rig who should be on a debate stage,” Mr. Hurd told CNN.

One critic of Mr. Trump who will appear on the debate stage is Vice President Pence, who has pivoted to leaning into his refusal to attempt to overturn the 2020 election. Mr. Pence came out in support of signing the pledge, saying, “I’m somebody that believes in a level playing field. Everybody ought to play by the same rules.”

One ironic facet of the loyalty pledge is that some states, like South Carolina, have similar provisions that candidates must agree to in order to participate in their primaries.

While there has been less of a spectacle around the state primary promises, Mr. Trump, on August 5, paid $50,000 to file for the South Carolina primary, which includes the pledge, as the Associated Press reports.

The form in question reads that the signatory does “generally believe in and intend to support the nominees of the Republican Party.”

With all of the attention around the debate directed toward the high drama of the pledge, Mr. Trump’s signing of the South Carolina form demonstrates that most of the calculus around his campaign’s decision to appear on stage probably doesn’t have to do with the pledge.

The debate will probably be one of the best opportunities for candidates to confront Mr. Trump ahead of the primaries, whether it be on policies, his record, or his many legal troubles, and it’s not clear what Mr. Trump has to gain from participating other than potentially being able to head off attacks from competitors.

That’s because Mr. Trump maintains a commanding and stable lead in the GOP primary. In a Kaplan Strategies Poll released Monday, Mr. Trump carried 48 percent support, the same level he posted in the pollster’s July poll.

The next closest candidate, businessman Vivek Ramaswamy, carried 11 percent support, and Mr. DeSantis was at 10 percent. Mr. Pence made the biggest gain of any candidate since July, polling at 8 percent in August versus 4 percent in July.