(Reuters) -Republican former President Donald Trump and former U.N. Ambassador Nikki Haley are competing to be their party's presidential nominee for the 2024 general election, while President Joe Biden is effectively the Democratic Party's nominee. Several third-party hopefuls are also running.
Here is a list of the candidates.
DONALD TRUMP
The Republican frontrunner with 64% support, according to Reuters/Ipsos polling, Trump has leveraged his unprecedented legal challenges, which include 91 indictments in four criminal cases, to boost his popularity among his base and raise money.
The former president scored victories in nominating contests in Iowa, New Hampshire, Nevada and South Carolina and is pushing for his allies to take over the leadership of the Republican National Committee ahead of the party's July convention.
Trump, 77, has said the criminal charges he faces are part of a political witch hunt designed to keep him from winning, a claim the U.S. Justice Department has denied.
Some of his legal challenges have reached the Supreme Court, including his eligibility for the ballot following the Jan. 6, 2021 attack on the U.S. Capitol as well as his claim of presidential immunity.
If elected to another four-year term, Trump has vowed revenge on his political enemies, said he would not be a dictator except "on day one" and pledged to pardon those imprisoned over the Jan. 6 attack. He also wants the power to replace some federal civil service workers with loyalists.
He sparked criticism from Western leaders after saying the U.S. would not defend NATO members that failed to spend enough on defense and would encourage Russia to attack them. He pressed congressional Republicans to stall a military aid package for Ukraine.
Trump has made immigration his top domestic campaign issue, declaring he would carry out mass deportations, create holding camps and utilize the National Guard.
He would also end birthright citizenship and expand a travel ban on people from certain countries. However, his opposition to a bipartisan deal in the Senate that would tighten immigration enforcement has stalled, if not killed, the bill.
He has repeated calls to impose the death penalty on drug dealers, said other alleged criminals could be shot dead, and suggested he would unilaterally send federal troops into Democratic-run localities.
On abortion, Trump has taken credit for the U.S. Supreme Court ruling overturning Roe v. Wade, but he has criticized some Republican-led states' six-week abortion bans. He said he supported in vitro fertilization (IVF) treatment access after an Alabama court ruling curtailed access in the state and raised questions about reproductive rights.
He has promised other sweeping changes, including eliminating Obamacare health insurance and undoing much of the Biden administration’s work to fight climate change.
NIKKI HALEY
A former South Carolina governor and Trump's ambassador to the United Nations, Haley, 52, has emphasized her relative youth compared to Biden, 81, and Trump, as well as her background as the daughter of Indian immigrants.
She has gained a reputation in the Republican Party as a solid conservative who could credibly tackle issues of gender and race, but she trails Trump in the polls, drawing 19% support among Republicans in the Reuters/Ipsos survey.
Trump has increasingly targeted her, lobbing racist attacks on her ethnicity and amplifying false claims about her eligibility for the White House despite her being born in South Carolina.
Haley, in turn, has sharpened her attacks on Trump, calling him "diminished" and "unhinged" and arguing he is too chaotic and divisive to be effective.
Haley has said she would pardon him if he is convicted on federal criminal charges.
She has vowed to stay in the race and has deployed campaign teams to at least eight states voting in presidential nominating contests through March 12.
Haley has pitched herself as a stalwart defender of American interests abroad, citing Trump's praise of dictators and slamming his support for Russian President Vladimir Putin after Russian opposition leader Alexei Navalny's death.
She also backs changes to Social Security and Medicare safety net programs for seniors and vowed to dramatically reduce the size of the U.S. government by shifting some federal programs to states.
She has said she personally opposes abortion and has sought national consensus on the issue. On IVF, she has said that she believes frozen embryos are babies but that she backs parents' rights over them.
Haley has called for making some tax cuts permanent and eliminating the federal gas tax.
DEMOCRATIC PARTY
JOE BIDEN
Biden, 81, already the oldest U.S. president ever, will have to convince voters he has the stamina for another four years in office, amid poor approval ratings and a special counsel report suggesting he suffered memory lapses.
Biden has blasted the report, and his allies say he believes he is the only Democratic candidate who can defeat Trump and protect democracy. The most recent Reuters/Ipsos poll put Biden at 34%, while Trump garnered 37% — close to the 2.9 percentage-point margin of error.
In announcing his candidacy, Biden declared he needed to defend American liberties and pointed to the deadly Jan. 6, 2021, attack on the U.S. Capitol by Trump supporters. Vice President Kamala Harris is again his running mate.
The economy will also factor in his reelection campaign. While the U.S. escaped an anticipated recession and is growing faster than economists expected, inflation hit 40-year highs in 2022 and the cost of essentials is weighing on voters.
Biden pushed through massive economic stimulus and infrastructure spending packages to boost U.S. industrial output, but he has received little recognition from voters for the latter.
Biden has led the response of Western governments to Russia's invasion of Ukraine, persuading allies to sanction Russia and support Kyiv, and he has been supportive of Israel in its conflict with Hamas in Gaza while pushing for more humanitarian aid.
However, he has faced sharp criticism from some fellow Democrats for not backing a permanent ceasefire in the Palestinian territory, where Gaza health officials say nearly 30,000 people have been killed, thousands of buildings have been damaged or destroyed, and residents have insufficient food, water and medical supplies.
Biden's handling of immigration policy has also been criticized by Republicans and Democrats as migrant crossings at the U.S.-Mexico border hit record highs during his administration.
In the Democratic Party's presidential nominating contests, Biden has easily won in New Hampshire, South Carolina, Nevada and Michigan.
DEAN PHILLIPS
Dean Phillips, a little-known U.S. congressman from Minnesota, announced in October he would mount a long-shot challenge to Biden because he does not believe the president can win another term.
The 55-year-old millionaire businessman and gelato company co-founder announced his bid in a one-minute video posted online, saying: "We've got some challenges ... We're going to repair this economy, and we are going to repair America."
Phillips failed to win any delegates in South Carolina and took second place in New Hampshire. He did not appear on the Nevada ballot.
MARIANNE WILLIAMSON
The best-selling author and self-help guru Marianne Williamson, 71, has re-launched her second, long-shot bid for the White House on a platform of "justice and love" less than a month after dropping out.
She ran as a Democrat in the 2020 presidential primary but dropped out of that race before any votes had been cast. In a statement, she said she had suspended her 2024 campaign because she was losing "the horse race" but was getting back in to fight Trump's "dark and authoritarian vision."
INDEPENDENTS
ROBERT F. KENNEDY JR
An anti-vaccine activist, Kennedy, 70, is running as an independent after initially challenging Biden for the Democratic nomination, but he is far behind in polling.
Some previous Reuters/Ipsos polls showed Kennedy could harm Biden more than Trump in the presidential election, where third-party candidates have affected the outcome of U.S. elections even without winning.
Trump's 6-percentage point lead over Biden held in a Reuters/Ipsos poll published on Jan. 25, the most recent to give respondents the option of voting for third-party candidates, including Kennedy, whose support stood at 8%.
Kennedy is the son of U.S. Senator Robert F. Kennedy, who was assassinated in 1968 during his own presidential bid.
A surprise Super Bowl ad heavily featuring his connection to his uncle, former President John F. Kennedy, angered his family members and prompted him to apologize.
He was banned from Instagram for spreading misinformation about vaccines and the COVID-19 pandemic but was later reinstated. He also lost a legal bid to force YouTube owner Google (NASDAQ:GOOGL) to reinstate videos of him questioning the safety of COVID vaccines.
CORNEL WEST
The political activist, philosopher and academic said in June he would launch a third-party bid for president that is likely to appeal to progressive, Democratic-leaning voters.
West, 70, initially ran as a Green Party candidate, but in October he said people "want good policies over partisan politics" and announced his bid as an independent. He has promised to end poverty and guarantee housing.
JILL STEIN
Jill Stein, a physician, re-upped her 2016 Green Party bid on Nov. 9, accusing Democrats of betraying their promises "for working people, youth and the climate again and again - while Republicans don’t even make such promises in the first place."
Stein, 73, raised millions of dollars for recounts after Trump's surprise 2016 victory. Her allegations yielded only one electoral review in Wisconsin, which showed Trump had won.