Joe Biden’s decision to step down as the Democratic Party’s nominee for president has opened the door for other contenders to become the Democratic nominee in November.

He has thrown his support behind Vice President Kamala Harris, and other prominent Democrats moved quickly to rally around her candidacy, but it is unclear how smooth her path to the party’s nomination is.

Here are some of the leading contenders for a spot on the Democratic ticket:

– Kamala Harris

Born in Oakland, California, Ms Harris calls former Supreme Court justice Thurgood Marshall an inspiration and talks often about growing up with parents deeply involved in the civil rights movement.

Her economist father and cancer specialist mother met as graduate students at the University of California, Berkeley, where Ms Harris recalled they spent time “marching and shouting about this thing called justice”. Mr Biden called her a “fearless fighter for the little guy”.

Ms Harris, who is black and also of south Asian descent, is the nation’s first female vice president and the first person of colour to hold that office. A graduate of Howard University, she is the also first person from a historically black college or university to be president or vice president.

She won her seat in the US Senate in 2016 after twice being elected California attorney general. She stressed her fights with big banks during the mortgage crisis, for-profit colleges that were financially exploiting students and environmental wrongdoers.

She has talked for years about criminal justice reform, and pushed for a different approach to non-violent crimes that emphasises rehabilitation instead of severe, one-size-fits-all punishment.

As vice president, Ms Harris was asked by Mr Biden to take on some of the most challenging tasks his administration has faced, including securing the nation’s borders.

As presiding officer of the US Senate, she has cast a record number of tie-breaking votes on legislation promoted by Democrats, who are defending a razor-thin majority in both houses of Congress in this year’s elections.

Harris, 59, is married to Los Angeles lawyer Douglas Emhoff.

– JB Pritzker

The Illinois governor, the richest politician holding office in the US, is an heir to the Hyatt Hotel fortune, a former private equity investor and philanthropist. His net worth of 3.4 billion dollars (£2.6 billion) puts him at No 250 on the Forbes 400 list of the richest Americans.

The 59-year-old won the nomination for governor in 2018, beating a crowded Democratic field. He beat incumbent Republican governor Bruce Rauner and inherited mountains of state debt, unpaid bills and ratings by Wall Street credit houses just above junk status because of Mr Rauner’s two-year feud with legislative Democrats that resulted in the state going without a budget plan.

Working with Democratic supermajorities in the House and Senate, Mr Pritzker has boasted balanced budgets and paid down billions of dollars in debt, prompting multiple credit upgrades. He has also overseen increased education funding, the centralisation of early childhood services, and new laws to make health insurance more comprehensive, accessible and affordable.

After receiving generally high marks for his handling of the Covid-19 pandemic, he defeated a Trump-endorsed Maga Republican with 55% of the vote, becoming the first Illinois governor to be elected to a second term in 16 years. He delivered a victory speech that sounded like it came from a national candidate, denouncing Mr Trump and asking, “Are you ready to fight?”

Even before his re-election, when there was speculation Mr Biden might not seek a second term, Mr Pritzker was criticised for saying he was happy being governor while travelling to the early primary state of New Hampshire and campaigning for or funding Democratic candidates nationally. He has continued to boost his coast-to-coast profile by bankrolling a political organisation called Think Big America which aims to protect abortion rights, and has supported state constitutional amendments to strengthen protections in Ohio, Arizona and Nevada.

– Gretchen Whitmer

The Michigan governor has rapidly risen in prominence within the Democratic Party since winning the 2018 gubernatorial election after serving for a decade and a half in the state legislature.

Her national profile grew significantly during the final years of Mr Trump’s presidency when she emerged as one of the Democratic Party’s most effective voices opposing the then-president. She delivered the Democratic response to Mr Trump’s 2020 State of the Union address and frequently clashed with him over how the federal government handled the Covid-19 pandemic.

Near the end of 2020, the FBI uncovered a plot to kidnap her, which led to nine men being convicted by jury or pleading guilty.

In her 2022 re-election campaign, Ms Whitmer focused on reproductive rights, resulting in a double-digit victory and passage of a voter-approved measure codifying abortion rights in the state. Her party also flipped both chambers of the state legislature, securing a Democratic triple for the first time in nearly four decades.

The massive Democratic victories in a swing state that Mr Trump won in the 2016 presidential election positioned Ms Whitmer as a leading advocate for reproductive freedom and a strong contender for a future presidential nomination.

Ms Whitmer — who was one of the top surrogates for Mr Biden’s re-election campaign — has long deflected questions about whether she has interest in higher office, telling the Associated Press earlier this month that she would not step in as a candidate this year if Mr Biden were to step aside.

But the 52-year-old has been working to boost her national profile. She met Mr Biden in 2020 as he considered who to select as a running mate and she is on a national press tour for her new memoir. She has also set up a national political action committee that has raised millions this election cycle.

– Gavin Newsom

The California governor is a native of San Francisco who got involved in politics by volunteering for Willie Brown’s 1995 campaign for mayor. Two years later, Mr Brown appointed Mr Newsom to a vacant seat on the San Francisco Board of Supervisors, where he was later elected and re-elected.

Mr Newsom then became mayor himself and received national attention in 2004 when he directed the San Francisco clerk to issue marriage licences to same-sex couples.

He was elected lieutenant governor in 2010 and pushed a progressive agenda when he successfully ran for governor eight years later. Now in his second term, he says he is “standing up for California values — from civil rights, to immigration, environmental protection, access to quality schools at all levels, and justice”, according to his official bio.

Mr Newsom, 56, has maintained a high national profile this year, challenging Republican presidential candidates in public appearances despite not being a candidate himself. He has been one of Mr Biden’s staunchest defenders even as criticism mounted after the president’s faltering debate performance. During an early July stop in New Hampshire on behalf of the president, Mr Newsom said: “He’s going to be our nominee.”

The governor was a baseball star at Santa Clara University. After graduating, he worked briefly in sales before starting a retail wine shop that grew into the PlumpJack Group, which includes restaurants, resorts and vineyards throughout California.

He is married to Jennifer Siebel Newsom. They have four children.

– Josh Shapiro

The Pennsylvania governor, long seen as a rising political star in the state, is halfway through his second year as governor after easily winning his last election by trouncing a far-right, Trump-endorsed candidate in the premier presidential battleground.

Mr Shapiro, 51, has been a surrogate for Mr Biden, backing the president in appearances on cable networks, and has years of experience making Mr Trump the focus of his attacks, first as state attorney general and now as governor.

If he joins a Democratic ticket, Mr Shapiro would become the first presidential nominee of Jewish heritage or the second vice presidential nominee of that background, after former Democratic senator Joe Lieberman of Connecticut in 2000.

Mr Shapiro has won three state-wide races — two as attorney general and one as governor — with a tightly scripted, disciplined campaign style, offering voters a lower-key alternative to the brash political star, US senator John Fetterman.

As governor, Mr Shapiro has begun to shed a buttoned-down public demeanour and become more confident and plain-spoken. In one recent MSNBC appearance, he said Mr Trump should “quit whining” and stop “shit talking America”.

Mr Shapiro has aggressively confronted what he viewed as antisemitism cropping up from pro-Palestinian demonstrations, and has professed solidarity with Israel in its drive to eliminate Hamas.

He is a staunch proponent of abortion rights in Pennsylvania and routinely touts his victories in court against Mr Trump, including beating challenges to the 2020 election results.

He has also positioned himself as a moderate on energy issues in the nation’s number two natural gas state and plays up the need for bipartisanship in the politically divided state government.

– Roy Cooper

The North Carolina governor has won six state-wide general elections over two decades in a state where Republicans routinely prevail in similar federal races and also control the legislature.

Mr Cooper, 67, has received strong job approval ratings as governor, benefitting from a booming state economy, for which his administration takes credit. He also portrays himself as a fighter for public education and abortion rights.

While Mr Cooper finally persuaded Republican legislators last year to expand Medicaid under the Affordable Care Act, other efforts have been thwarted by a General Assembly with veto-proof majorities which have eroded his formal powers.

A native of small-town Nash County, about 50 miles east of Raleigh, Mr Cooper was his high school quarterback and head of the Young Democrats at the University of North Carolina, where he obtained his undergraduate and law degrees. Coop, as he was known to friends, came home and worked at his father’s law firm.

He upset the Democratic incumbent in a 1986 state House primary race and was elected to the General Assembly. He served 14 years there and later became the Senate majority leader.

Mr Cooper was elected attorney general in 2000, a position he held for 16 years. In that post, he is best known nationally for declaring three former Duke University lacrosse players innocent after they were wrongly accused of sexual assault by an escort service dancer.

He unseated another incumbent in 2016, this time Republican governor Pat McCrory by roughly 10,000 votes. A top campaign issue was the “bathroom bill” Mr McCrory signed requiring transgender people to use public toilets that corresponded with the sex on their birth certificates. As governor, Mr Cooper quickly reached an agreement with legislators to partially repeal the law.

His time as governor was also marked by restricting business and school activity during the Covid-19 pandemic. He won re-election in 2020 by 4.5 percentage points, even as Mr Trump won the state’s electoral votes.

Cooper and his wife Kristin have three grown daughters.

— Mark Kelly

The US senator for Arizona leveraged his career as an astronaut to build a brand as a moderate in a state that long supported Republicans.

In his two campaigns — the first in 2020 to finish the late Republican senator John McCain’s last term, and the second two years later for a full term — Mr Kelly has earned more votes than any other Democrat on the ballot. He outpolled Mr Biden, who narrowly won Arizona, by 2 percentage points in 2020.

Mr Kelly’s first turn in the national political spotlight came through tragedy. His wife, then-US representative Gabrielle Giffords, was shot in the head while meeting constituents outside a store in Tucson, a shooting that left six people dead and spawned an early reckoning with political violence and partisan rancour.

Ms Giffords’ improbable survival made her a national inspiration but snuffed out a promising political career of her own. She and Mr Kelly went on to found a gun-control advocacy group, and she has been a powerful surrogate as Mr Kelly has taken her place in politics.

In the Senate, he has focused on national security and the military as well as the drought plaguing the US West. He was instrumental in crafting a bill signed by Mr Biden to boost US semiconductor manufacturing.

Mr Kelly was a Navy test pilot and flew 39 combat missions during the Gulf War before joining Nasa, where he flew three missions on the space shuttle.

Originally from New Jersey, he settled with Ms Giffords in Tucson after retiring from Nasa and the Navy.