Updated

Who is Ron DeSantis?

Florida Gov. Ron DeSantis will once again try to establish himself as the top challenger to former President Donald Trump and change the narrative after a series of setbacks the past few months, which triggered weeks of negative stories spotlighting his campaign’s overspending, staff layoffs, change of leadership and other setbacks.

"I know from the military, when you’re over the target, that’s when you’re taking flak. And if you look really in the last six to nine months, I’ve been more attacked than anybody else. Biden, Harris, the media, the left, other Republican candidates," DeSantis said. "And there’s a reason for that, because people know that I’m the biggest threat. So we view it as positive feedback. We’ll be ready to do what we need to do to deliver our message, but we absolutely expect that, and we’ll be ready for it."

SIGN UP NOW! WATCH THE FIRST GOP PRESIDENTIAL DEBATE ON FOXNEWS.COM

Republican Florida Gov. Ron DeSantis

Republican Florida Gov. Ron DeSantis speaks during the annual Feenstra Family Picnic at the Dean Family Classic Car Museum in Sioux Center, Iowa, on Saturday, May 13, 2023.  (Rebecca S. Gratz for The Washington Post via Getty Images)

Asked whether his first debate strategy included punching back at rivals on the stage, DeSantis told Fox News, "Yes, that means defending ourselves but more importantly showing why we are the leader to get this country turned around."

GOP REPUBLICAN PRESIDENTIAL DEBATE: LIVE UPDATES

Who is Nikki Haley?

Former South Carolina governor and UN Ambassador Nikki Haley announced in February that she would be running for president, seeking the Republican nomination for the 2024 election.
Born in Bamberg, South Carolina, Haley has long been viewed by political pundits as a potential GOP presidential contender.

Haley has crisscrossed the country the past two years through her political group Stand for America, helping fellow Republicans running in the 2022 elections. Her travels brought her numerous times to Iowa, New Hampshire, and Nevada, which hold the first, second and fourth contests in the Republican presidential nominating calendar. Haley’s home state of South Carolina votes third in the GOP primary schedule.

FIRST REPUBLICAN PRESIDENTIAL DEBATE AN ‘AWESOME OPPORTUNITY’ FOR CANDIDATES TO SCORE BREAKOUT MOMENTS

"America is not past our prime, it's just that our politicians are past theirs," Haley said in her first campaign speech, as the crowd chanted "USA" and "Nikki."

Nikki Haley Moms for Liberty Philadelphia

2024 presidential candidate Nikki Haley gives remarks at Moms for Liberty's Joyful Warriors National Summit in Philadelphia on June 30, 2023. (Fox News Photo/Joshua Comins)

Haley has called for years for the U.S. to be more aggressive in combating the threat from Beijing and in June called for a fundamental change in the U.S. outlook to the threat from the East.

In late July, Haley unveiled an extended plan to deal with the Chinese Communist Party. The plan includes a pledge to roll back Biden-era green energy mandates, which she says are a giveaway to Beijing.

While polls indicate Haley is an underdog compared to other candidates like former President Donald Trump and Florida Gov. Ron DeSantis, Haley has a history of winning tough elections.
In 2004, she defeated the state’s longest-serving state House member in the GOP primary on her way to winning a state legislative seat. And six years later, she topped a congressman, the state’s lieutenant governor, and the attorney general in the Republican gubernatorial primary, ahead of her general election victory.

WISCONSIN IN THE SPOTLIGHT AHEAD OF 2024 ELECTION

Haley is the daughter of immigrants from India who grew up to become South Carolina’s first female governor and the nation’s first female governor of Asian American heritage.

Following her tenure as governor of the Palmetto State, Haley served in Trump's administration as the U.S. Ambassador to the UN, leaving at the end of 2018 on good terms with the then-president.

Who is Vivek Ramaswamy?

Vivek Ramaswamy, a health care and tech sector entrepreneur, conservative commentator and author who has become a crusader in the culture wars, declared his candidacy in the Republican presidential primary in February.

Born in Cincinnati, Ramaswamy quickly made a name for himself on the campaign trail. Ramaswamy, who was dubbed "the CEO of Anti-Woke Inc." in a New Yorker magazine profile last year, said earlier this year that his campaign is "about the unapologetic pursuit of excellence in our country. It means you believe in merit; that you get ahead in this country not on the color of your skin but on the content of your character and your contributions."

AMERICA'S IN A ‘NATIONAL IDENTITY CRISIS,’ RAMASWAMY WARNS, SAYS HE WILL BRING ‘REVOLUTION’

In an interview with Fox News Digital in August, Ramaswamy said that he wants to answer "the question of what it means to be American in the year 2023."

Republican presidential candidate Vivek Ramaswamy

Vivek Ramaswamy, chairman and co-founder of Strive Asset Management, speaks at the Republican Party Of Iowa's annual Lincoln Dinner in Des Moines, Iowa, US, on Friday, July 28, 2023. (Rachel Mummey/Bloomberg via Getty Images)

"I’m 37 years old. When you ask people my age and younger what it means to be American today, you get a blank stare," he said.

Ramaswamy has called for a "total decoupling" from Communist China, which he argues is a greater threat to America today than the Soviet Union was during the Cold War because China makes the "shoes on our feet and the phones in our pockets."

As the son of Indian migrants who legally came through America's "front door," Ramaswamy is a strong supporter of merit-based immigration and would not grant leniency for those who broke the law when entering the country.

NIKKI HALEY SWIPES RAMASWAMY, SCOTT ON CHINA AHEAD OF FIRST PRIMARY DEBATE: ‘PEOPLE WHO DON’T UNDERSTAND'

Other top priorities of his include "restoring free speech," which would involve making political expression a civil right and banning Big Tech censorship executed at the behest of the government, and "dismantling" affirmative action and the "new climate religion," which he calls a "cancer on the American soul."

Who is Tim Scott?

South Carolina Republican Sen. Tim Scott announced in May that he would seek the GOP nomination for president.

Known for his fundraising prowess, Scott, the only Black Republican in the Senate, entered the White House race with his campaign coffers well stocked. Scott reported nearly $22 million cash on hand at the end of last year — funds left over from the senator’s convincing 25-point re-election victory in November in reliably red South Carolina.

A pair of Scott-aligned super PACs started 2023 with roughly $16 million in the bank, thanks to contributors from numerous Republican mega-donors including Oracle co-founder Larry Ellison.

TIM SCOTT RELISHES DEBATE ‘CONTRAST OPPORTUNITY’ TO PRESENT CONSERVATIVE ‘COMMONSENSE SOLUTIONS’

"Here’s a kid that grew up in North Charleston, South Carolina, mired in poverty, in a single parent household. To think about one day being the President of the United States just tells me that the evolution of the American soul continues to move toward that more perfect union," Scott told Fox News in May.

scott holding mic on campaign trail

Senator Tim Scott holds a 'major announcement' in North Charleston, SC at his alma mater, Charleston Southern University in the Buccaneer Field House in Charleston, SC, United States on May 22, 2023 (Peter Zay/Anadolu Agency via Getty Images)

Prior to his campaign announcement, Scott, who has served in the Senate since 2013 and was born in North Charleston, South Carolina, had been viewed by political pundits as a potential 2024 Republican presidential contender.

While the senator had repeatedly demurred when asked about a White House bid, he hinted last November at a possible future run during his re-election victory celebration by telling the story of how he took his grandfather to the polls in 2012, and that his grandfather proudly voted for him as well as for Democrat Barack Obama, the nation’s first Black president.

"I wish he had lived long enough to see perhaps another man of color elected President of the United States," Scott said, before adding "but this time let it be a Republican."

ND GOV DOUG BURGUM SUFFERS INJURY AHEAD OF GOP PRESIDENTIAL DEBATE, WILL DECIDE PARTICIPATION AFTER DOC VISIT

Who is Chris Christie?

Former two-term New Jersey Gov. Chris Christie officially launched his second White House bid in June, joining a crowded field of presidential hopefuls vying for the 2024 Republican nomination.

Declaring his candidacy during a town hall event at Saint Anselm College in Manchester, New Hampshire — the state with the first GOP presidential primary — Christie said: "I can't guarantee you success in what I'm about to do. But I guarantee you that at the end of it, you will have no doubt in your mind who I am and what I stand for and whether I deserve it."

In his speech, Christie railed against the division that he said has driven Americans into smaller groups, brought about by the likes of former Presidents Barack Obama and Donald Trump. He also touted America's role throughout its history in "fighting evil" across the world.

Chris Christie

Chris Christie, former governor of New Jersey, during a Bloomberg Television interview in Washington, DC, US, on Wednesday, July 19, 2023. Christie has made debating Donald Trump the centerpiece of his presidential campaign, saying he's the only challenger who will confront the former president directly, a lesson he says he learned in his unsuccessful 2016 primary campaign.  (Andrew Harrer/Bloomberg via Getty Images)

Christie focused a portion of his campaign announcement speech on taking jabs at former President Donald Trump, describing him as a "leader who won't admit any of his shortcomings" and referring to him as "Voldemort," the infamous villain in the "Harry Potter" novels.

Born in Newark, New Jersey, Christie held the highest office in the state from 2010 to 2018 and was the deep-blue state's last Republican governor. 

He first ran for president in the 2016 cycle. At the time, Christie placed all his chips in New Hampshire, but his campaign crashed and burned after a disappointing and distant sixth-place finish in New Hampshire, far behind Trump, who crushed the competition in the primary en route to winning the nomination and eventually the White House.

RAMASWAMY SAYS HE EMBRACES THE MEDIA HEAT AHEAD OF FIRST GOP DEBATE: ‘IT MAKES ME STRONGER AS A CANDIDATE’

Christie became the first among the other GOP 2016 contenders to endorse Trump, and for years he was a top outside adviser to the then-president and chaired Trump’s high-profile commission on opioids. However, the two had a falling out after Trump’s unsuccessful attempts to overturn his 2020 election loss to now-President Joe Biden. Over the past two years, Christie has become one of the most vocal Trump critics in the GOP.

Who is Mike Pence?

Former Vice President Mike Pence filed paperwork with the Federal Election Commission to launch his campaign for the 2024 Republican presidential nomination in early June.

Pence was serving as the governor of Indiana when then-presidential candidate Donald Trump named him his running mate in 2016. For four years, Pence served as the loyal vice president to Trump.

Former vice president Mike Pence

Former Vice President Mike Pence and his family join him as he gives remarks to a small crowd on Wednesday, Jan. 20, 2021 at Columbus Municipal Airport in Columbus, Ind.Ini 0120 Pence Vp

However, everything changed on Jan. 6, 2021, as demonstrators — including some chanting "hang Mike Pence" — stormed the U.S. Capitol aiming to upend congressional certification of President Biden’s Electoral College victory that was overseen by Pence.

In the more than two years since the end of the Trump administration, the former president and vice president have drifted further apart. Pence has repeatedly rebuked his former boss, calling him out by name while discussing Trump's claim that Pence could have overturned the results of the 2020 presidential election.

Pence has described the 2021 protest at the Capitol as "tragic," insisting that "it dishonored the millions of people who had supported our cause around the country." He has emphasized that he did "the right thing" and performed his "duty under the Constitution." He has also noted a number of times that he and Trump may never "see eye to eye on that day."

X SUSPENDS DESANTIS PAC'S ACCOUNT HOURS BEFORE DEBATE

Trump loyalists will likely never forgive Pence, whom they view as a traitor for refusing to reject the 2020 election results.

In announcing his campaign, Pence became the first running mate in eight decades to run against his former boss, since Vice President John Nance Garner unsuccessfully challenged President Franklin Roosevelt in the 1940 election.

Born in Columbus, Indiana, Pence has touted the Trump-Pence administration’s policy successes in stump speeches but contrasts himself with the controversial former president in terms of tone and tenor.

"People around the country want us to see us restore a threshold of civility in our political debate," Pence emphasized. "You can disagree without being disagreeable. People that know me know I take very strong stands. I’m conservative, but I’m not in a bad mood about it."

He has stressed that "should we enter the fray in this campaign in the days ahead, we’re going to bring those principles, but we’re going to bring a commitment to civility that I think the American long to see."

AT FIRST REPUBLICAN DEBATE, WATCH FOR THESE 6 KEY THINGS. THEY COULD MAKE BIDEN A ONE-TERM PRESIDENT

Pundits had long viewed Pence as a likely 2024 contender, as he spent the past two years crisscrossing the country to campaign and help raise money for Republicans running in the 2022 elections. Those travels took Pence multiple times to Iowa, New Hampshire, South Carolina and Nevada — the first four states to vote in the Republican presidential nominating calendar — as he strengthened relationships in the early voting presidential primary and caucus states that usually precede the launch of a White House campaign.

Who is Doug Burgum?

Before becoming the 33rd governor of North Dakota, Doug Burgum established himself as a successful businessman in the software industry. 

Burgum, 67, steered his one-time small business, Great Plains Software, into a $1 billion software company. His business — and its North Dakota-based workers — were eventually acquired by Microsoft, and Burgum stayed on board as a senior vice president.

North Dakota Gov. Doug Burgum

North Dakota Gov. Doug Burgum at the state Capitol on April 10, 2020, in Bismarck, N.D. (Mike McCleary/The Bismarck Tribune via AP, File)

In 2016, the then first-time candidate and long shot convincingly topped a favored GOP establishment contender to secure the Republican nomination in North Dakota before going on to a landslide victory in the gubernatorial general election in the solidly red state. Burgum was overwhelmingly re-elected in 2020 to a second term as governor.

DEMOCRATS BLANKET MILWAUKEE WITH PRO-BIDEN MESSAGES AHEAD OF GOP PRIMARY DEBATE

"Governor Burgum is looking forward to sharing his focus on the economy, energy and national security at the August debate," Burgum campaign spokesman Lance Trover said last month. "In less than 7 weeks, Governor Burgum has exceeded all the requirements for the debate. As a Governor and business leader Doug knows how to fix the economy, unleash American energy and win the Cold War with China." 

Fox News' Paul Steinhauser, Adam Shaw, Andrew Miller, Brandon Gillespie and Kyle Morris contributed reporting.