The RNC announced the participants on Monday but did not mention Trump. The former president dominates the field, with his indictments in four separate criminal cases boosting his popularity among Republican voters, and has said there is little political upside for him to debate his rivals.
Here is a list of participants in the debate, set to start at 9:00 p.m. ET (0100 GMT Thursday):
RON DESANTIS
After a glitch-filled campaign launch on Twitter in May, DeSantis, 44, has positioned himself to the right of Trump on a number of key social issues such as abortion.
But his well-funded campaign has struggled to gain traction and his top donor has said he won't give the Florida governor more money unless he adopts a more moderate approach.
DeSantis is Trump's top rival but remains far behind the former president in opinion polls - at just 13% in the latest Reuters/Ipsos poll of Republican voters compared to Trump's 47% support. He has sacked staff and rebooted his campaign several times since May, but those steps have has done little to boost his candidacy.
MIKE PENCE
Trump's vice president has broken with his former boss over the Jan. 6, 2021, attack by Trump supporters on the U.S. Capitol, while Pence was inside the building. Pence, 64, says "history will hold Trump accountable" for his role in the attack.
The former Indiana governor, a staunch conservative, is appealing directly to the evangelical Christian community and secured 8% support in Reuters/Ipsos' latest poll conducted Aug. 2-3.
VIVEK RAMASWAMY
A former biotechnology investor and executive, Ramaswamy, 38, started a firm in 2022 to pressure companies to abandon environmental, social and corporate governance initiatives. The political outsider has stoked grassroots chatter as a potential alternative to Trump and garnered 7% in the latest Reuters/Ipsos poll.
NIKKI HALEY
A former governor of South Carolina and Trump's ambassador to the United Nations, Haley, 51, has emphasized her relative youth compared to Biden and Trump as well as her background as the daughter of Indian immigrants.
Haley has gained a reputation in the Republican Party as a solid conservative who has the ability to address issues of gender and race in a more credible fashion than many of her peers. She has also pitched herself as a stalwart defender of American interests abroad. She has about 5% support among Republican voters in the latest Reuters/Ipsos poll.
TIM SCOTT
The only Black Republican U.S. senator has low name recognition outside his home state of South Carolina, but his optimism and focus on unifying his divided party have helped him draw a contrast with a more aggressive approach from Trump and DeSantis. Scott supporters, however, acknowledge that while his sunny demeanor is a selling point, it may not be enough to win.
Scott, 57, attracted 2% support among Republicans, according to Reuters/Ipsos polling.
ASA HUTCHINSON
The former Arkansas governor launched his bid for the White House in April with a call for Trump to step aside to deal with his indictment. Hutchinson, 72, has touted his experience leading the deeply conservative state as proof he can deliver on policies Republican voters care about, citing tax cuts and job creation initiatives.
Still, his name recognition remains limited outside Arkansas and just 1% of registered Republicans polled by Reuters/Ipsos said they would support him.
CHRIS CHRISTIE
Chris Christie, 60, advised Trump's White House campaign but became a vocal critic of the former president after the Jan. 6, 2021, attack. The former New Jersey governor has stepped up his verbal attacks as Trump faces a growing number of criminal charges.
Christie saw no support among Republicans in the latest Reuters/Ipsos poll, which has a credibility interval of about 6 percentage points.
DOUG BURGUM
Burgum, 67, is serving his second term as North Dakota's governor after selling his software business to Microsoft Corp in 2001. A proponent of low taxes and fewer regulations, he has sought to portray himself as a traditional conservative with a focus on the economy and national security. He also secured no support among the 355 registered Republicans polled by Reuters/Ipsos in early August.
