WASHINGTON (Reuters) – The largest Democratic field in the modern U.S. political era is competing for the party’s 2020 presidential nomination.

The diverse group of more than 20 vying to challenge President Donald Trump, the likely Republican nominee, includes seven U.S. senators. A record six women are running, as well as black, Hispanic and openly gay candidates who would make history if one of them becomes the party’s nominee.

Some candidates are beginning to gain traction. Others are still looking for their chance to break through.

Two Republicans are also competing for their party’s nomination.

DEMOCRATIC TOP TIER

Here are the Democrats who are ranked in the top eight in the RealClearPolitics national polling average.

JOE BIDEN

The leader in polls on Democratic presidential contenders, Biden waited until late April to enter the race, launching his bid by taking a direct swipe at Trump. Biden, 76, who served eight years as vice president under President Barack Obama and 36 years in the U.S. Senate, enters in the middle of a Democratic debate over whether a liberal political newcomer or a centrist veteran is needed to win back the White House. Biden relishes his “Middle-Class Joe” nickname and touts his working-class roots.

BERNIE SANDERS

The senator from Vermont lost the Democratic nomination in 2016 to Hillary Clinton but is making a second try. In the 2020 race, Sanders, 77, will have to fight to stand out in a packed field of progressives touting issues he brought into the Democratic Party mainstream four years ago. His proposals include free tuition at public colleges, a $15 minimum wage and universal healthcare. He benefits from strong name recognition and a robust network of small-dollar donors.

ELIZABETH WARREN

The 69-year-old senator from Massachusetts is a leader of the party’s liberals and a fierce critic of Wall Street who was instrumental in creating the Consumer Financial Protection Bureau. She has focused her presidential campaign on her populist economic message, promising to fight what she calls a rigged economic system that favors the wealthy. She also has proposed eliminating the Electoral College, breaking up tech companies, and sworn off political fundraising events to collect cash for her bid.

KAMALA HARRIS

The first-term senator from California would make history as the first black woman to gain the nomination. Harris, 54, the daughter of immigrants from Jamaica and India, announced her candidacy on the holiday honoring slain civil rights leader Martin Luther King Jr. She supports a middle-class tax credit, Medicare for All healthcare funding reform, the Green New Deal and the legalization of marijuana. Her track record as San Francisco’s district attorney and California’s attorney general has drawn scrutiny in a Democratic Party that has shifted in recent years on criminal justice issues.

PETE BUTTIGIEG

The 37-year-old mayor of South Bend, Indiana, emerged from underdog status to build momentum with young voters. A Harvard University graduate and Rhodes Scholar at the University of Oxford, he speaks seven languages and served in Afghanistan with the U.S. Navy Reserve. He touts himself as representing a new generation of leadership needed to combat Trump. Buttigieg would be the first openly gay presidential nominee of a major American political party.

BETO O’ROURKE

The former three-term Texas congressman jumped into the race on March 14, and has been jumping on to store countertops ever since to deliver his optimistic message to voters in early primary states. O’Rourke, 46, gained fame last year for his record fundraising and ability to draw crowds ahead of his unexpectedly narrow loss in the U.S. Senate race against Republican incumbent Ted Cruz. O’Rourke announced a $6.1 million fundraising haul for the first 24 hours of his campaign, besting his Democratic opponents. But with progressive policies and diversity at the forefront of the party’s nominating battle, O’Rourke faces a challenge as a wealthy white man who is more moderate on several key issues than many of his competitors.

CORY BOOKER

Booker, 50, a senator from New Jersey and former mayor of Newark, gained national prominence in the fight over Brett Kavanaugh’s Supreme Court nomination. Booker, who is black, has made U.S. race relations and racial disparities a focus of his campaign, noting the impact of discrimination on his family. He embraces progressive positions on Medicare coverage for every American, the Green New Deal and other key issues, and touts his style of positivity over attacks.

AMY KLOBUCHAR

The third-term senator from Minnesota was the first moderate in the Democratic field vying to challenge Trump. Klobuchar, 58, gained national attention in 2018 when she sparred with Brett Kavanaugh during Senate hearings for his Supreme Court nomination. On the campaign trail, the former prosecutor and corporate attorney supports an alternative to traditional Medicare healthcare funding and is taking a hard stance against rising prescription drug prices. Klobuchar’s campaign reported raising more than $1 million in its first 48 hours.

TRYING TO BREAK THROUGH

The field also includes many Democrats who are trying to find a way to break through. Some hold public office and have managed to generate an early fundraising base, while others are still trying to raise their profile.

JULIAN CASTRO

The secretary of housing and urban development under President Barack Obama would be the first Hispanic to win a major U.S. party’s presidential nomination. Castro, 44, whose grandmother immigrated to Texas from Mexico, has used his family’s personal story to criticize Trump’s border policies. Castro advocates a universal prekindergarten program, supports Medicare for All and cites his experience to push for affordable housing. He announced his bid in his hometown of San Antonio, where he once served as mayor and a city councilman. His twin brother, Joaquin Castro, is a Democratic congressman from Texas.

BILL DE BLASIO

The New York City mayor emerged as a progressive standard-bearer in 2013, when he won the first of two four-year terms at the helm of the country’s biggest city on a platform of addressing income inequality. But he has struggled amid middling approval ratings and some political setbacks to build a national profile. De Blasio, 57, can point to a number of policy wins in New York, including universal prekindergarten, a higher minimum wage and paid sick leave. He has called Trump a “bully” and a “con artist” and criticized his administration’s positions on immigration, climate change and social welfare.

KIRSTEN GILLIBRAND

Gillibrand, known as a moderate when she served as a congresswoman from upstate New York, has refashioned herself into a staunch progressive, calling for strict gun laws and supporting the Green New Deal. The senator for New York, who is 52, has led efforts to address sexual assault in the military and on college campuses, and she pushed for Congress to improve its own handling of sexual misconduct allegations. On the campaign trail, she has made fiery denunciations of Trump. She released her tax returns for the years 2007 through 2018, offering the most comprehensive look to date at the finances of a 2020 White House candidate, and has called on her rivals to do the same.

TULSI GABBARD

The Samoan-American congresswoman from Hawaii and Iraq war veteran is the first Hindu to serve in the U.S. House of Representatives. After working for her father’s anti-gay advocacy group and drafting relevant legislation, she was forced to apologize for her past views on same-sex marriage. Gabbard, 37, slammed Trump for standing by Saudi Arabia after the murder of journalist Jamal Khashoggi. She endorsed Bernie Sanders during his 2016 presidential campaign.

ANDREW YANG

The entrepreneur and former tech executive is focusing his campaign on an ambitious universal income plan. Yang, 44, wants to guarantee all Americans between the ages of 18 and 64 a $1,000 check every month. The son of immigrants from Taiwan, Yang also is pushing for Medicare for All and proposing a new form of capitalism that is “human-centered.” He lives in New York.

JAY INSLEE

The Washington state governor has made fighting climate change the central issue of his campaign. As governor, Inslee, 68, has moved to put a moratorium on capital punishment and fully implement the Affordable Care Act, commonly known as Obamacare, and accompanying expansion of Medicaid health coverage for the poor. He has not settled on a position on Medicare for All but does support the Green New Deal backed by progressives. Inslee spent 15 years in Congress before being elected governor in 2012.

TIM RYAN

The moderate nine-term congressman from a working-class district in the battleground state of Ohio has touted his appeal to the blue-collar voters who fled to Trump in 2016. Ryan, 45, pledges to create jobs in new technologies and to focus on public education and access to affordable healthcare. He first gained national attention when he unsuccessfully tried to unseat Nancy Pelosi as the House Democratic leader in 2016, arguing it was time for new leadership. A former college football player, he also has written books on meditation and healthy eating.

JOHN DELANEY

The former U.S. representative from Maryland became the first Democrat to enter the 2020 race, declaring his candidacy in July 2017. Delaney, 56, plans to focus on advancing only bipartisan bills during the first 100 days of his presidency if elected. He is also pushing for a universal healthcare system, raising the federal minimum wage and passing gun safety legislation.

JOHN HICKENLOOPER

The 67-year-old former Colorado governor has positioned himself as a centrist and an experienced officeholder with business experience. He is the only Democratic presidential candidate so far to oppose the Green New Deal plan to tackle climate change, saying it would give the government too much power in investment decisions. During his two terms as governor, Colorado’s economy soared and the Western state expanded healthcare, passed a gun control law and legalized marijuana. The former geologist and brew pub owner is among the many candidates who have refused to take corporate money. He previously served as mayor of Denver.

STEVE BULLOCK

The Democratic governor of Montana, re-elected in 2016 in a conservative state that Trump carried by 20 percentage points, has touted his electability and ability to work across party lines. Bullock, 53, has made campaign finance reform a cornerstone of his agenda, and emphasizes his success in forging compromises with the Republican-led state legislature on bills to expand Medicaid, increase campaign finance disclosures, bolster pay equity for women and protect public lands.

ERIC SWALWELL

The third-term congressman from a district south of San Francisco cited tackling student debt and gun violence among the reasons he jumped into the Democratic primary race. Swalwell, 38, is among the younger candidates vying for the 2020 Democratic nomination. He served on the House Intelligence Committee and founded the Future Forum, a group of more than 25 Democratic lawmakers that visits universities and community colleges to discuss issues important to millennial voters like student loan debt and climate change.

SETH MOULTON

An Iraq War veteran and member of Congress, Moulton, 40, was first elected to the U.S. House of Representatives in 2014. Moulton served in the Marines from 2001 to 2008. He became a vocal critic of the Iraq War, saying no more troops should be deployed to the country. He has advocated stricter gun laws, saying military-style weapons should not be owned by civilians. Moulton supports the legalization of marijuana and told a Boston radio station in 2016 that he had smoked pot while in college. After Democrats took control of the House in 2018, Moulton helped organize opposition to Nancy Pelosi’s bid to again become speaker.

MICHAEL BENNET

Bennet, 54, who is serving his second full six-year term as a senator for Colorado, has centered his political career on improving the American education system. He previously ran Denver’s public schools. Bennet is not well known nationally, but has built a network of political operatives and donors helping elect other Democrats to the Senate. During the partial U.S. government shutdown in January, he garnered national attention criticizing Republicans for stopping the flow of emergency funds to Colorado.

MIKE GRAVEL

The 89-year-old former senator made a little-known run for the Democratic nomination in 2008 and is taking another stab at the White House. One of his top issues is advocating for direct democracy, which would remove power from Congress and have voters decide policy changes. Gravel represented Alaska in the U.S. Senate from 1969 to 1981. He lost re-election in the 1980 race. Since leaving the Senate, Gravel worked in real estate and finance. In 2008, after failing to gain any traction in the Democratic contest, he also made an unsuccessful bid to be the Libertarian nominee for president.

WAYNE MESSAM

Messam, 44, defeated a 16-year incumbent in 2015 to become the first black mayor of the Miami suburb of Miramar. He was re-elected in March. The son of Jamaican immigrants, he played on Florida State University’s 1993 national championship football team, and then started a construction business with his wife. He has pledged to focus on reducing gun violence, mitigating climate change and reducing student loan debt and the cost of healthcare.

MARIANNE WILLIAMSON

The 66-year-old New York Times best-selling author, motivational speaker and Texas native believes her spirituality-focused campaign can heal America. A 1992 interview on Oprah Winfrey’s show propelled Williamson to make a name for herself as a “spiritual guide” for Hollywood and a self-help expert. She is calling for $100 billion in reparations for slavery over 10 years, gun control, education reform and equal rights for lesbian and gay communities. In 2014, she made an unsuccessful bid for a House seat in California as an independent.

THE REPUBLICANS

President Trump is the clear favorite to win the Republican nomination and there has been criticism among his opponents that party leadership have worked to make it impossible for a challenger. But he will still face at least one challenger.

DONALD TRUMP

Serving in his first term, the 72-year-old real estate mogul shocked the political establishment in 2016 when he successfully secured the Republican nomination and then won the White House. His raucous political rallies and prolific use of Twitter were credited with helping him secure victory. After running as an outsider, Trump is now focusing his message on the strong economy and criticism of Democrats as he vies for re-election.

BILL WELD

Former Massachusetts Governor William Weld is mounting a long-shot bid to unseat Trump in the Republican primary. Weld ran unsuccessfully for vice president in 2016 as a Libertarian. He has been a persistent critic of Trump, saying when he launched his 2020 campaign that “the American people are being ignored and our nation is suffering.”

(Reporting by Ginger Gibson; Additional reporting by Joseph Ax; Editing by Alistair Bell, Jonathan Oatis and Bernadette Baum)