Candidates for the 2024 Republican presidential nomination are making their final pitches to voters as election season heats up.
A crowded field including several big-name and dark-horse contenders is now beginning to thin out.
All are seeking to unseat front-runner Donald Trump, as the former president continues to dominate in national opinion polls.
The eventual winner will challenge the presumptive Democratic nominee, President Joe Biden, in the general election of November next year.
Florida Governor Ron DeSantis was once viewed as the candidate most capable of defeating Mr Trump in a head-to-head race, but he has since faded.
Serving two terms as a little-known member of the House of Representatives, the former naval officer was boosted to the governorship by Mr Trump's endorsement in 2018.
After romping to re-election in last year's midterms by more than 1.5 million votes, the largest margin in the state in more than four decades, he was touted as the man to carry his fellow Floridian's "America First" movement forward.
At 44 years old, the Harvard and Yale-educated lawyer is still a relative newcomer in US politics.
But he has seen his star rise considerably since becoming governor, a role in which he has positioned himself as an enthusiastic culture warrior.
He has backed legislation to defund diversity and inclusion programmes, ban teaching on gender identity in public schools, ban drag shows and gender-affirming care for minors, restrict abortions and loosen gun laws.
Under his tenure, Republican voters outnumber Democrats in the state for the first time.
The governor has touted his record as a "blueprint" for conservative leadership, and supporters have presented him as a drama-free alternative to re-nominating the former president.
But an awkward personal brand, campaign trail flubs, financial troubles and an onslaught from the Trump camp have taken the wind out of the sails of a once-promising bid.
Now Mr DeSantis is focusing much of his energy on beating Mr Trump in Iowa, the first state in which Republicans cast their primary ballots, even as polls suggest his campaign has lost its momentum. National polls show him sitting in a distant second place.
Nikki Haley was the first major Republican candidate to launch a campaign against Mr Trump, jumping into the race in mid-February.
Born in South Carolina to Punjabi Sikh immigrants, Ms Haley, 51, became the youngest governor in the country in 2009.
She earned national attention after calling for the removal of the Confederate flag from the South Carolina Capitol.
Despite saying she was "not a fan" of Mr Trump in 2016, she later accepted his nomination to be the US ambassador to the United Nations, a tenure marked by her dramatic exit from a UN Security Council meeting as a Palestinian envoy was speaking.
Her campaign, which includes a call for mandatory mental competency tests for politicians over 75 years old, has stressed the need for "a new generation" of leaders.
At campaign events and debates, the lone woman in the race has sought to find middle ground on hot-button issues like abortion, and demonstrated her foreign policy expertise.
As a result, Ms Haley has seen her poll numbers rise since the first debate in August. Her campaign is hoping a strong performance in the first three nominating states of Iowa, New Hampshire and her native South Carolina can position her as the chief alternative to Mr Trump.
Vivek Ramaswamy, 37, launched a dark-horse bid for the White House during a late February appearance on the Fox News channel.
An Indian-American biotech entrepreneur with no previous political experience, he was a regular fixture on Fox host Tucker Carlson's daily programme, formerly the most-watched cable news show in the US.
The Harvard and Yale graduate ran a pharmaceutical company from 2014 to 2021, then co-founded Strive Asset Management.
He is also the author of Woke, Inc: Inside Corporate America's Social Justice Scam.
Mr Ramaswamy argues the country is in the midst of a national identity crisis driven by a decline in faith, patriotism and meritocracy. He frequently touts "10 truths" on God, gender and other ideas.
He has also positioned himself as the most fervent defender of Mr Trump in the Republican field, even going so far as to vow that - if elected president - he would pardon the ex-president of any crimes.
The political newcomer enjoyed a brief polling bump after a show-stealing performance at the first Republican debate, but rivals have ridiculed his lack of experience.
Mr Ramaswamy also recently drew controversy over remarks he made about the 9/11 terror attacks.
"I think it is legitimate to say 'How many police, how many federal agents were on the planes that hit the twin towers?'" he said in an interview with the Atlantic.
After he claimed to have been misquoted, something he has often said, the magazine released audio of the exchange proving it was an accurate quote.
Chris Christie announced his candidacy in June at a town hall event in New Hampshire - which traditionally holds one of the earliest contests in the primary race.
Mr Christie, 60, served two terms as New Jersey governor from 2010-18. Though massively popular in his first term, his second was overshadowed by a political scandal involving bridge lane closures - part of an alleged political vendetta against a Democratic mayor - and another involving beach closures.
He left office with a job approval rating of 14%, the lowest in state history.
Before being elected governor, he had served as New Jersey's top prosecutor under President George W Bush from 2002-08, and famously sent Charles Kushner - the father of Mr Trump's son-in-law Jared - to prison.
After a 2016 presidential bid with some notable moments flamed out, Mr Christie allied himself with Mr Trump, leading the incoming president's transition team and preparing him for debates against Mr Biden in 2020.
But he has become a vociferous critic of Mr Trump since the US Capitol riots.
The sharp-tongued politician has said Mr Trump is "a TV star, nothing more, nothing less. Let me suggest to you that in putting him back in the White House, the re-runs will be worse than the original show".
But his campaign's lack of traction suggests that Republican voters have little appetite for an acerbic Trump critic.
Former two-term Arkansas Governor Asa Hutchinson announced his bid in an April interview with ABC News, just days after Mr Trump was indicted on criminal charges in New York.
Mr Hutchinson, 72, has said Mr Trump's legal problems are "a sideshow and distraction" that should prompt him to withdraw from the race.
The former attorney and businessman was the youngest federal prosecutor in the nation under the Ronald Reagan administration.
He also served two terms in the US House of Representatives, including as a prosecutor in Bill Clinton's impeachment trial, and was George W Bush's Drug Enforcement Administration (DEA) chief.
Presenting himself as a "non-Trump" candidate with experience and a record of leadership across multiple roles, he has vowed to lean into "common sense, consistent conservatism".
But after barely qualifying for the first Republican debate, he has been unable to make the stage the next two times.
North Dakota Governor Doug Burgum confirmed a run for the White House in June, saying: "If you want more small-town common sense in Washington and our big cities, we'll make that happen."
The former software executive is little-known on the national scene, but he has overseen significant economic expansion as the leader of his deep-red state.
He subscribes to staunchly conservative social policies, on issues like abortion and LGBT rights.
But he has barely factored in the race, with largely forgettable appearances at the first two debates.
Who has dropped out?
After a nearly five-month campaign, former vice-president Mike Pence called it quits.
Mr Pence had languished in recent polls and had struggled to gain the support of Republican voters.
South Carolina Senator Tim Scott suspended his campaign in mid-November, saying voters had signalled it was not his time to run. He has not endorsed any of his rivals.
Miami's 45-year-old Cuban-born mayor, Francis Suarez, was the only Hispanic candidate in the race. He was the first to drop out.
Former Texas congressman Will Hurd announced he was suspending the race and backing Nikki Haley.
The conservative talk radio host and ex-candidate for California governor, Larry Elder, dropped out after accusing the Republican party of having "rigged the rules of the game" to keep him out of the debates.
Perry Johnson, a 75-year-old businessman touting a plan to shave 2% in federal spending every year, dropped out of the race in late October.