Image copyright AP Image caption From left, Woo Kwok-hing, John Tsang and Carrie Lam are vying to be Hong Kong's next leader

Hong Kong chooses its next leader on Sunday in a vote overshadowed by fierce divisions over stalled political reform in the city.

It is the first chief executive election since Hong Kong was brought to a standstill by mass pro-democracy rallies in 2014. Protesters wanted fully democratic elections for their leader - but Beijing refused.

Pro-democracy campaigner Joshua Wong has called the current electoral process "a selection rather than an election".

In a nutshell: What is happening?

A small group of mainly pro-Beijing electors will choose from three candidates to succeed outgoing leader CY Leung.

His deputy, Carrie Lam, is Beijing's choice for the top job. But her main rival, former finance chief John Tsang, is the public's favourite, according to opinion polls.

The pro-democracy camp are backing Mr Tsang in a likely unsuccessful bid to keep Ms Lam out. The third candidate is retired judge Woo Kwok-hing.

Image copyright AFP Image caption Hong Kong's unpopular leader CY Leung is stepping down after five years in office

So who does get to vote?

Ordinary Hong Kong people have no say. Instead, Hong Kong's 1,200-seat Election Committee, a mostly pro-Beijing body, will decide on the next leader.

Media playback is unsupported on your device Media caption Hong Kong election: The nanny, Mr Pringles or the judge?

The Legislative Council's 70 members - half of whom are directly elected - form part of this committee. But most of the members are elected by business, professional or special interest groups. Critics say entities that lean towards Beijing are given disproportionately large representation.

In the most recent selection for the Election Committee, pro-democracy activists secured 325 seats on the committee - the highest number ever. However, this does not give them enough seats to control who becomes the next chief executive.

How does it work?

Candidates need 601 votes to win. If no candidate reaches this total, the top two candidates go to a second round.

Incumbent CY Leung limped over the line with 689 votes in 2012 - despite having Beijing's backing. "689" then became a pejorative nickname for the unpopular leader - and Beijing will want its choice, Ms Lam, to do much better.

Image copyright AP Image caption Carrie Lam has the support of China's leaders - but Hong Kong residents are not convinced

Who's in the lead?

In the nominating round, Carrie Lam secured 580 votes, just shy of the winning mark. Woo Kwok-hing got 180 votes and John Tsang secured 165, just over the qualifying threshold of 150.

Beijing has made it clear that it backs Ms Lam and there are multiple reports of lobbying behind the scenes on her behalf.

John Tsang is seen as the main threat, given the high levels of public support for him. Though pro-establishment, he is seen as the more moderate choice, and more than 300 pro-democracy committee members say they will vote for him. It's the first time the pan-democrat camp has backed an establishment candidate.

Mr Tsang also has support from some pro-establishment voters, but this is unlikely to be enough to defeat Ms Lam.

So what are the candidates like?

Carrie Lam has served as Hong Kong's chief secretary - the number two position - for five years and has almost four decades of public service behind her.

She has been praised as a strong administrator but is despised by the pro-democracy camp for backing a mainland ruling saying that while residents could vote for their leader in 2017, they could only choose from a list of pre-approved candidates. She's been nicknamed CY2.0 - another version of the outgoing Mr Leung.

She's also been accused of being out of touch with voters after gaffes including a bizarre search for toilet paper and a failure to use a transport swipe card.

Image copyright AP Image caption John Tsang has emerged as the strongest challenger to Ms Lam

John Tsang is also a career civil servant and Hong Kong's longest-serving financial secretary.

Praised for having a common touch - he's got almost 270,000 Facebook followers - he's called on Hong Kong's divided residents to come together.

But he's been criticised as financial secretary in the past for under spending on social welfare to preserve budget surpluses.

His nickname is "Pringles", or "Uncle Chips", for his resemblance to a snack mascot.

Mr Woo served as a High Court judge for many years. He is seen as moderate and pro-establishment, and is popular with some activists and young people who feel he is not "tainted" by politics. But analysts say Ms Lam and Mr Tsang as seen as the two contenders with a chance of winning.

Would either bring Hong Kong closer to the vote?

It seems very unlikely. In 2015 pro-democracy lawmakers rejected Beijing's offer of universal suffrage for the chief executive election if the candidates were pre-approved by the Chinese government, and the proposal was voted down. As a result, this election is being conducted under the existing process.

Carrie Lam advocated on behalf of Beijing's position and has expressed reservations about restarting the political reform process, saying "We need to ask ourselves very seriously whether we have any prospect of achieving a consensus before we trigger another intense debate in society".

John Tsang initially expressed similar sentiments but then promised to relaunch the process "with the greatest determination and courage". But he says Beijing's framework must be the starting point for any movement.

Regardless of either stance, there has been no sign Beijing is willing to compromise on this. There are also signs it is getting bolder about interventions in Hong Kong, including its lobbying for Ms Lam, its role in blocking two pro-independence lawmakers from the legislature and the recent abduction of a billionaire from a hotel in Hong Kong.

Image copyright AFP Image caption Massive street protests shut down parts of Hong Kong in late 2014

So what's the mood?

The mass pro-democracy rallies may have ended but many young people remain unhappy.

Joshua Wong, who led the 2014 protests, has refused to back any candidate and will be protesting outside the election venue.

"No one will deny that Carrie Lam is the worst one and a nightmare for us - but it doesn't mean we can put aside our principles and endorse any pro-China candidate," he told AFP news agency.

A human rights group is organising a march as the polls take place and Hong Kong police say 1,800 officers will be deployed - more than the total number of electors.

But it is also true to say that during the political ructions of the last three years - from Occupy protests to the politicised "fishball" clashes - there have been Hong Kongers who expressed support for the status quo.