Former US vice-president Joe Biden fuelled speculation this week that he could be preparing for a presidential run when he delivered a speech at the residence of Irish ambassador Dan Mulhall in Washington. Having kept a relatively low profile since leaving the White House at the end of the Obama administration, his appearance was the latest public engagement by the former senator in recent weeks.

Twenty months into the presidency of Donald Trump, focus is already turning to who might run for the White House in 2020.

That Democrats across the country are energised is not in question. The shock victory of Donald Trump and the growing realisation that he is following through on much of his “America First” agenda has shaken Democrats to their core.

But for a party still nursing the wounds of the bitter primary battle between Hillary Clinton and Bernie Sanders in 2016, there are many unanswered questions about the ideological direction of the party.

The victory of left-wing candidates such as 28 year-old Alexandria Ocasio-Cortez, who unseated Democrat stalwart Joe Crowley in a primary battle in New York this year, suggests a renewed energy behind the Bernie Sanders wing of the party.

But equally, the success of more centrist Democrats such as Conor Lamb, who won a special election in a reliably Republican area of Pennsylvania this year, suggests that a move to the left is not always the answer for a party looking to contest seats in Republican-leaning districts.

The first primaries – the process by which nominees for each party are selected – are still 17 months away. Iowa and New Hampshire are expected to hold their caucus and primary in the first week of February 2020. But there are signs that prospective candidates are already testing the waters.

Securing delegates in Iowa and New Hampshire is considered crucial for aspiring nominees.

By this point in the 2016 presidential campaign cycle, Hillary Clinton had attended the annual “steak-fry” in Indianola, Iowa. Though Clinton would not declare that she was formally running until the following April, her appearance at the event in September 2014, attended by 7,000 people, was an indication of her impending presidential run.

To date, there have been relatively few sightings of potential Democratic candidates in these crucial states, though it is rumoured that potential candidates such as Kamala Harris and Cory Booker have begun deploying staff to the states to help candidates running in this year’s mid-term elections. It’s a strategy often adopted by would-be nominees as a way of building political support in the state and making local contacts.

A clearer picture of who will take on Republicans in 2020 is likely to emerge after November. Traditionally, the end of the mid-term election season is the starting-gun for the presidential race. The focus is currently on mid-term election day on November 6th, but by early next year prospective candidates are likely to emerge. The long lead-up time to US presidential elections means that several prospective nominees are likely to fall before the primary season begins.

Here are 10 candidates who may become the Democrat to win back the White House from Donald Trump.

1. Kamala Harris

The 53-year-old senator from California is one of the top contenders for the Democratic nomination in 2020. A lawyer by training, she was attorney general of California between 2011 and 2017, before her election to the US senate in November 2016.

Born in Oakland, California to immigrant parents, she is seen as being on the left of the Democratic Party. In recent weeks she rose to national prominence through her tough questioning of Supreme Court nominee Brett Kavanaugh during his testimony to the Senate Judiciary Committee.

Publicly, she said she has “not ruled out” running in 2020. There are several signals that she may be considering a run. She has been actively building an online campaign, spending hundreds of thousands of dollars on a web advertising and a digital campaigning consultancy. She announced this summer that she is writing a book – another rite of passage for presidential hopefuls. The Truths We Hold: An American Journey will be published early next year.

As a woman from an ethnic minority background, she could be the face of change that the Democrats need post-Trump. But, as one Washington strategist put it recently: “California might be ready for her, but I don’t know if the rest of the country is.”

2. Cory Booker

Hot on the heels of Kamala Harris for the Democratic nomination is New Jersey senator Cory Booker. A former mayor of Newark, 49-year-old Booker was elected as the first African-American senator of New Jersey in 2013.

In an interview with New York magazine this week, he said it would be “irresponsible” not to consider running against Donald Trump. “Of course the presidency will be something I consider. It would be irresponsible not to,” he said.

While his own Senate seat is not up for grabs this November, he has been actively campaigning for Democratic candidates around the country ahead of the mid-terms.

Like Harris, he has positioned himself on the left of the party. He also shone during the Brett Kavanaugh confirmation hearings early this month. He memorably declared an “I am Spartacus” moment when he indicated willingness to knowingly violate senate rules by releasing classified documents related to the nominee. But eyebrows were raised when it emerged the following day that it was planned to release those documents anyway.

3. Kirsten Gillibrand

Senator Gillibrand has emerged as a strong contender for the Democratic nomination in 2020. The 51-year-old lawyer from upstate New York took Hillary Clinton’s Senate seat when she was appointed secretary of state in 2009.

Viewed as a strong ally of the Clintons, she raised the ire of Clintonites last year at the height of the #MeToo movement when she said that Bill Clinton should have resigned over the Monica Lewinsky scandal. In Congress she has long championed the cause of victims of sexual violence in the military and on college campuses. That Gillibrand publicly broke with the Clintons could be an indication of the waning power of the Clinton brand within the Democratic party.

An experienced politician (she was was already a two-term member of the House of Representatives when she took over Clinton’s seat), Gillibrand has not confirmed if she will run.

But she has provoked attacks on Twitter by Trump aides, a sure sign to many that Republicans are worried about her potential candidacy. She has been one of the most forceful critics of Trump in the Senate, voting against virtually all his nominees. “Everything we care about is at risk with this president,” she said in May.

Like many potential candidates, her policy positions have moved further to the left in recent years.

Two years after she decided not to seek the Democratic nomination for president, Massachusetts senator Elizabeth Warren is believed to be in the running this time around. One of the leading progressive voices in US politics, Warren has a loyal fanbase, many of whom believe she is a more credible alternative to Bernie Sanders.

The former Harvard law professor has long campaigned on a left-wing social agenda, pledging to redistribute wealth and resources to the poorer in society and waging a war against big banks.

The 69-year-old senator is expected to easily win her Senate seat, which is up for grabs this November. She has been appearing at Democratic events around the country throughout the year, prompting speculation that she could be assessing her levels of support for a presidential run.

Sources in Washington say that Warren has already been quietly building relationships with well-placed journalists in the national press.

Unlike Sanders, she has worked with Republican colleagues in the Senate, partnering with senators on the other side of the aisle to co-sign legislation on issues including marijuana and predatory lending.

She can also boast the dubious claim of being the subject of Trump’s tweets. He has mocked her as “Pocahontas”, a reference to the Oklahoma native’s indigenous American ancestry.

5. Bernie Sanders

Despite losing the Democratic nomination to Hillary Clinton in 2016, Bernie Sanders has not ruled out a run next time around. While Sanders’s “Feel the Burn” candidacy ultimately fizzled out, his legacy has not, with many on the left of the Democratic party hoping he will run.

His supporters still believe that he would have beat Donald Trump in 2016 – they argue that Sanders was ahead in polling in key swing states such as Wisconsin ahead of the election. This view has been bolstered by analysis that found many Sanders supporters in the rust-belt states switched their vote to Trump once Clinton was chosen as the Democratic nominee.

Sanders already has a campaign infrastructure from his 2016 nomination bid, which would give him a headstart on rivals.

But one of the main factors working against him is his age. The Vermont senator would be 79 if he was to be elected as president. The other factors weighing against him are the same doubts that marred his chances the first time round. Many Democrats believe that, while his popularity within the Democratic fold is high, he is less appealing to the general populace.

6. Joe Biden

Former vice-president Joe Biden may have left the White House, but his increasing public appearances in recent weeks have prompted rumours of a return to frontline politics.

Biden, a long-time senator from Pennsylvania who was tapped by president Barack Obama to become vice-president, failed to dampen speculation at an event in the Irish ambassador’s residence this week. After delivering a speech focused on hope and change, he was asked if he was planning a run. “I’m running to change the attitude,” he replied with a smile.

Like Sanders, Biden’s main stumbling block is his age – he turns 76 in November. He also twice ran unsuccessfully for the Democratic nomination – in 1998 and 2008. He considered running in 2016, but ultimately decided against it, backing Hillary Clinton instead.

His decision took place in the context of huge personal trauma following his son Beau’s death from cancer. But many of his supporters believe he would have beaten Trump, particularly given his connection with blue-collar workers, a traditionally Democratic constituency that voted Republican in November 2016.

Biden is expected to campaign vigorously for Democratic candidates in the mid-term elections ahead of November 6th. Whether he will make one more run for president is uncertain. As one Democratic strategist recently put it: “He may be old, but in the current climate the prospect of a steady, experienced hand like Joe Biden may be just what the country needs.”

7. Beto O’Rourke

The 45-year-old guitar-playing, skateboarding congressman from Texas has shaken up the political landscape this year.

A member of the House of Representatives since 2013, the little-known O’Rourke is taking on Republican grandee Ted Cruz for one of Texas’s two Senate seats in November. Remarkably, polls are showing that O’Rourke has a chance in this traditionally Republican state. Boosted by a strong online presence, and vigorous fund-raising, he is mounting a real challenge to Cruz in his home state.

Born and raised in El Paso, Texas to an Irish-American family, he is known by the nickname “Beto” – a common abbreviation for Roberto in this heavily Latino district. He is fluent in Spanish – a big plus in a state with a growing Hispanic population.

Even if he fails to win the Senate seat this time around, observers believe that he is cementing the nationwide name recognition needed for a presidential run. Whether 2020 is his year or not, he is definitely a Democrat to watch.

The name of Michael Bloomberg has long been tossed about as a potential presidential candidate.

The former mayor of New York, who amassed a fortune through his Bloomberg media empire, remains a highly visible figure in US public life. In 2016 he was expected to run as an independent, but ultimately backed Hillary Clinton.

A front-page story in the New York Times this week reported that Bloomberg is mulling a run for president as a Democrat. But there is at least one glaring problem – he was first elected as New York mayor as a Republican.

Bloomberg has already committed to spending millions on Democratic campaigns in the run-up to the mid-terms. As a billionaire and former Republican, his challenge will be convincing the progressive wing of the party that he can represent their interests. His stop-and-frisk policy while New York mayor, which overwhelmingly affected black and Latino men, has also been seized upon by critics.

At 76, this would likely be his last chance at the presidency. While senior figures in the Democratic Party such as Nancy Pelosi have spoken highly of him, whether he will actually seek the nomination is another matter.

9. Mitch Landrieu

He may not have the profile – or deep pockets – of Michael Bloomberg, but another former mayor is being touted as a possible Democratic candidate. Mitch Landrieu, the former mayor of New Orleans, rose to national prominence last year after he ordered the removal of two confederate statues from the city. His book, In the Shadow of Statues, helped boost his national profile, winning him appearances on some of the country’s most-watched talk-shows.

In a country looking for change, his status as a Southern Democrat could be a vote-getter. He has reportedly caught the eye of senior aides in the Obama and Clinton camps.

However, in an interview in June, he said that Joe Biden would be the “ideal candidate” to take on Donald Trump if he had to pick today, prompting speculation that he may not run.

As well as Landrieu, another mayoral candidate could be in the running. Eric Garcetti, the mayor of Los Angeles, has confirmed that he is considering a run. The photogenic 47-year-old is just back from a trip to Ohio, a key battleground state, adding to speculation that he is testing the national political waters.

10. Michael Avenatti

Every presidential race has its maverick candidates. So far, Michael Avenatti is fitting the bill. The 47-year-old from California has shot to national fame as lawyer for Stormy Daniels, the adult film star who claims to have had an affair with Donald Trump. Avenatti is one of the few names to confirm that he is actively considering a run for president. In a sign that he is taking his bid seriously, he visited Iowa last month, meeting with several Democrats in the State.

“The moment we are living in is grave. It is critical. Trump doesn’t have the character, the heart, the knowledge or the wisdom to be president of the United States of America,” he told the Iowa Democratic Wing Ding dinner, a grassroots fundraiser.

Avenatti’s main flaw is that he has never run for political office before – but then again, neither had Donald Trump.

Avenatti evidently believes he has what it takes to defeat the US president, arguing that Democrats must fight back. “When they go low, I say, we hit harder,” he said in Iowa, amending former first lady Michelle Obama’s famous quote. Whether or not he emerges as a serious candidate, expect to see lots of him in the coming months as the Trump administration’s legal difficulties with Stormy Daniels continue.